Rothamsted Meteorological Station

  • Description: Rothamsted has one of the longest continuous sets of meteorological recordings in the world. Rain and wind direction have been measured since 1853, temperature since 1878 and sunshine from 1890. Currently over 25 different variables are recorded each day. The weather station was automated in 2004, with a range of sensors attached to an automatic data logger; some manual observations continued until May 2007. Hourly data from 2004 are available from the e-RA Curators.

    Annual rainfall averages 763.5mm (1991-2010), but ranges widely from 380mm in 1921 to 1059mm in 2012. Mean annual temperature 1878-1990 was 9 °C; average annual temperature is now more than 1°C higher than the 1878-1990 average (see Mean Annual Air Temperature).

    In 2018, the World Meteorological Organisation (WMO) officially designated Rothamsted as a Centennial Station, joining a global network of sites recognised by the WMO for recording reliable observations for over 100 years.

    Real-time hourly, daily and yearly weather charts for Rothamsted are available on-line over 28 days or 365 days (rolling) via the Rothamsted Environmental Change Network (ECN) pages.

  • Date Start: 1853
  • Date End: Ongoing
  • Recording: Daily at 0900 GMT
  • Automatic data recording began: Jan 1st 2004
  • Manual recording finished: May 2007
  • Address: Rothamsted Research, West Common, Harpenden, Hertfordshire, AL5 2JQ, United Kingdom
  • OS Grid Ref: TL 13154 13272
  • Latitude/Longitude: 51.8066 N -0.3602 E
  • Altitude: 128 m asl

Key Contacts

  • Andy Macdonald

  • Role: Principal Investigator
  • Organisation: Rothamsted Research
  • Address: West Common, Harpenden, Hertfordshire, AL5 2JQ, United Kingdom
  • Tony Scott

  • Role: Data Manager
  • Organisation: Rothamsted Research
  • Address: West Common, Harpenden, Hertfordshire, AL5 2JQ, United Kingdom
  • Sarah Perryman

  • Role: Data Manager
  • Organisation: Rothamsted Research
  • Address: West Common, Harpenden, Hertfordshire, AL5 2JQ, United Kingdom
  • Margaret Glendining

  • Role: Data Manager
  • ORCID: https://orcid.org/0000-0002-6466-4629
  • Organisation: Rothamsted Research
  • Address: West Common, Harpenden, Hertfordshire, AL5 2JQ, United Kingdom

Funding

Rothamsted Meteorological data available in ROTHMET

Daily meteorological data recorded at Rothamsted, Harpenden, Hertfordshire available from 1853. Since January 1st 2004, meteorological records have been measured by a range of sensors attached to an automatic data logger; some manual observations continued to be made until May 2007. The datalogger was updated from a CR23X to a CR3000 on 20/06/2019.

Hourly data from 2004 is available from the e-RA Curators.

Variable Units Description Dates recorded Methods of measurement

Air temperature

TMAX °C Maximum temperature 1878-current date

TMAX is recorded over the 24 hour period up to 0900GMT, for the previous day's maximum

TMIN is recorded over the 24 hour period up to 0900GMT, for the current day's minimum

Since 2004 recorded by thermistors (electronic temperature probes, Campbell Scientific, type 107). TMAX originally recorded using a mercury-in-glass sheathed column maximum thermometer and TMIN using a spirit-in-glass with indicator bar minimum thermometer, both housed in a naturally aspirating temperature screen.

TMIN °C Minimum temperature 1878-current date
WETB °C Wet bulb temperature, measuring temperature of evaporation 1915-January 2014

Recorded at 0900GMT

Since 2004 recorded by thermistor (electronic temperature probe, Campbell Scientific, type 107). Originally measured with a mercury-in-glass column thermometer, the bulb covered by a cotton wick kept moist from a water reservoir. Housed in a naturally aspirating temperature screen. Used to calculate relative humidity (RELH), vapour pressure (VAP) and dew point (DEWP).

Discontinued in January 2014 and replaced by a Relative Humidity Sensor to measure RELH.

DRYB °C Dry bulb temperature 1915-current date

Recorded at 0900GMT

Since 2004 recorded by thermistor (electronic temperature probe, Campbell Scientific, type 107). Originally measured with a sheathed mercury-in-glass column thermometer, housed in a naturally aspirating temperature screen. Used to calculate relative humidity (RELH), vapour pressure (VAP) and dew point (DEWP).

DEWP °C Dew point 1915-current date;

Recorded at 0900GMT

Derived from DRYB and RELH since 2014, after the method of Buck (1981). (see derived variables), calculated within the datalogger.

Derived from DRYB and WETB until 2013, (see derived variables), calculated within the datalogger. Before 2004 it was calculated from hygrometric tables.

GRSMIN °C Grass minimum temperature 1909-current date

Recorded at 0900GMT

Since 2004 recorded by thermistor (electronic temperature probe, Campbell Scientific, type 107), approx. 1cm above grass surface, measurement period 1800-0900GMT, measured according to Met Office Procedure. Previously recorded using a glass sheathed spirit-in-glass with indicator bar minimum thermometer, with bulb just touching grass surface, with cotton sleeve and anti-condensation shield on upper part of the instrument, minimum temperature 0900-0900GMT.

Soil temperature under grass

G10T °C Soil temperature under grass at 10cm 1931-current date

Recorded at 0900GMT

Since 2004 recorded by thermistors (electronic temperature probes, Campbell Scientific, type 107), buried in the soil at the appropriate depth.

First recorded using specially adapted thermometers set at depths of 4, 8, 12, 24 and 48 inches (10, 20, 30, 61 and 122cm) under grass cover. Since 1972, re-set to 10, 20, 30, 50 and 100cm (Penman 1974). G10T, G20T and G30T were in direct contact with the soil. G30T was discontinued in 1997.

The thermometers used to record E30T, E50T and E100T were encased in a glass sheath in a metal tube, enabling easy removal to read the temperature. The bulb was set in paraffin wax to minimize rapid temperature fluctuations when the thermometer was removed from the soil.

G20T °C Soil temperature under grass at 20cm 1931-current date
G30T °C Soil temperature under grass at 30cm 1931-1997
E30T °C Soil temperature under grass at 30cm 1915-1957; 1997-current date
E50T °C Soil temperature under grass at 50cm 1948-current date
E100T °C Soil temperature under grass at 100cm 1945-current date

Soil temperature under bare soil

S10T °C Bare soil temperature at 10cm 1931-current date

Recorded at 0900GMT

Since 2004 recorded by thermistors (electronic temperature probes, Campbell Scientific, type 107), buried in the soil at the appropriate depth.

First recorded using specially adapted thermometers set at depths of 10, 20 and 30cm (4, 8 and 12 inches) under bare soil (S10T, S20T and S30T). S10T and S20T were in direct contact with the soil. The thermometers used to measure S30T were encased in a glass sheath in a metal tube, enabling easy removal to read the temperature. The bulb was set in paraffin wax to minimize rapid temperature fluctuations when the thermometer was removed from the soil.

S20T °C Bare soil temperature at 20cm 1931-current date
S30T °C Bare soil temperature at 30cm 1931-current date

Rainfall (precipitation)

RAIN mm Rainfall from original 5 inch gauge 1853-1879; 1914-current date

Total rainfall over 24 hours recorded at 0900GMT

RAIN was originally recorded in a 5 inch (12.7cm) diameter rain gauge built in a garden near the laboratory in 1852. The water collected was measured in a graduated cylinder until about 1880. The gauge was then moved to the current meteorological enclosure. In 1948, a 12.7cm (5 inch) copper rain gauge of Meteorological Office standard was installed within a 0.3 m high, 1.5 m radius turf wall retained by brick to reduce wind eddies.

Since Sept 9th 2020 it has been recorded with an SBS500 tipping bucket rain gauge, funnel diameter 25.2cm and calibrated to tip at 0.2mm, manufactured by Environmental Measurements Ltd (EML), supplied and calibrated by Campbell Scientific. It is no longer sited within the turf wall, as the aerodynamics of the gauge means that it should not be affected by wind eddies. From 2004 to 8th Sept 2020 it was measured by an electronic tipping bucket rain gauge of 25.4cm (10 inch) diameter, ARG100 (manufactured by EML, supplied and calibrated by Campbell Scientific), calibrated to tip at 0.2mm, within the original turf wall. The old 5 inch manual copper rain gauge is still used to manually measure precipitation fallen as snow when the tipping bucket rain gauge is blocked with snow or ice.

Data from RAIN is missing between 1880-1914, and it is recommended that for a complete run of data from a standard rain gauge RAIN5 should be used for 1880-1914.

"Missing values" There are many instances before 2004 when no data is shown for RAIN (rather than zero). This is because a 'trace' of rain, snow, mist, dew or fog was manually recorded. A 'trace' is less than 0.05mm. For most purposes a missing value can be assumed to be zero.

EML state that the "ARG100 rain gauge typically captures over 5% more rainfall than most traditionally-shaped cylindrical gauges due to its unique aerodynamic shape and reduced evaporation-loss properties". This has found to be the case at Rothamsed. A review of the differences in rainfall capture between the ARG100 and the manual 5 inch gauge at Rothamsted was conducted. Using a double mass curve analysis, annual data from 1990-2017, and looking at each added year from 2004 (when the ARG100 was introduced), the overall correction factor is 1.1 or 10%. This means that the ARG100 captures 10% more rainfall than the manual 5 inch gauge. This correction is only applicable to annual and monthly totals, and to the variable RAIN at Rothamsted (ie ROTHMET only). It is not applicable to RAINL or RAIN5. To convert 5 inch data to ARG100 data, multiply by 1.1. To convert ARG100 data to 5 inch, divide by 1.1. We recommend that when you download data that spans both gauges, you multiply the 5 inch data by 1.1. Please contact the e-RA Curators for more information.

RAIN5 mm Rainfall from second 5 inch gauge 1873-1987

Total rainfall over 24 hours recorded at 0900GMT

The variable RAIN5 was originally recorded in another 5 inch (12.7cm) cooper rain gauge, established in 1873. Data was not recorded in e-RA after 1987. RAIN and RAIN5 are two separate gauges, hence the values do not exactly agree.

Data from RAIN is missing between 1880-1914, and it is recommended that for a complete run of data from a standard rain gauge RAIN5 should be used for 1880-1914.

"Missing values" There are many instances before 1987 when no data is shown for RAIN5 (rather than zero). This is because a 'trace' of rain, snow, mist, dew or fog was manually recorded. A 'trace' is less than 0.05mm. For most purposes a missing value can be assumed to be zero.

RAINL mm Rainfall in the 1/1000th acre rain gauge, to be used with the drainage data (DR20, DR40 and DR60) ONLY 1853-current date

Total rainfall over 24 hours recorded at 0900GMT

RAINL measures rain in a gauge of 1/1000th of an acre (4.047 sq metres), built in 1852/53. The gauge was constructed of timber with a lead funnel. Rain was collected daily in carboys and weighed to estimate the amount of rain. In 1873 a new gauge was installed and the carboys replaced by galvanized iron calibrated cylinders to measure rainfall. The old gauge was replaced by an identical new one in 1992. For the early history see Lawes et al., 1881.

From 2004 onwards the calibrated cylinders were replaced by an electronic tipping bucket rain gauge ARG100 (manufactured by Environmental Measurements Ltd (EML), supplied and calibrated by Campbell Scientific), calibrated to tip with every 0.0025mm of rain. In July 2010 the lead lining was stolen and it was replaced by a new stainless steel funnel of grade 316 and dimensions 2213mm x 1829mm in February 2011. No RAINL data was collected for this period.

Since 2004, when the met station was automated, RAINL may have been underestimating rainfall when rain is intense. RAINL should only be used in conjunction with the drainage data, which has the same surface area (DR20, DR40, DR60). For general daily rainfall data please use RAIN. It is recommended that if you use RAINL, RAIN should be used as a check.

"Missing values" There are many instances before 2004 when no data is shown for RAINL (rather than zero). This is because a 'trace' of rain, snow, mist, dew or fog was manually recorded. A 'trace' is less than 0.05mm. For most purposes a missing value can be assumed to be zero.

RDUR hr Rainfall duration 1931-current date

Total hours of rainfall over 24 hours recorded at 0900GMT

Since 2004 measured by an electronic tipping bucket rain gauge ARG100 (manufactured by Environmental Measurements Ltd, supplied and calibrated by Campbell Scientific), used to record RAIN. Originally measured by a Negretti and Zamra natural siphon rain recorder. Rain was collected in a float chamber and recorded on a daily chart on a clock drum, which recorded 10mm of rain before siphoning began and the recording restarted at the bottom of the chart. In 1978 this was replaced with a Cassella recorder with a diameter of 20.3cm.

Drainage data (percolation)

DR20 inches Drainage from drain gauge at 20 inch (51cm) depth 1870-current date

Total drainage over 24 hours recorded at 0900GMT

Three drain gauges (DR20, DR40 and DR60) were constructed at Rothamsted in 1870. They consist of undisturbed blocks of soil 20, 40 and 60 inches (51, 102 and 152 cm) deep and are equal in area to the rain gauge of 1/1000th of an acre (RAINL).

The gauges were constructed by digging under and around the block of soil, placing perforated plates underneath at the required depth and bricking up the sides. The soil around the gauges remained undisturbed throughout the construction process.

Since 2004 drainage has been measured by electronic tipping bucket rain gauge ARG100 (manufactured by Environmental Measurements Ltd (EML), supplied and calibrated by Campbell Scientific). Drain water was originally measured by weighing the carboys of collected water (as for RAINL), but these were replaced by calibrated cylinders. All three drain gauges remain as originally built. The soil has never been deep cultivated or cropped and the top is kept clear by hand weeding.

DR40 inches Drainage from drain gauge at 40 inch (102cm) depth 1870-current date
DR60 inches Drainage from drain gauge at 60 inch (152cm) depth 1870-current date

Sunshine

SUN hr Hours of sunshine 1890-current date

Total sun hours over 24 hours, 0000GMT to 2400GMT

Since 2004 sunshine has been calculated using the Campbell-Stokes equation from solar radiation measured using a CM3 Kipp and Zonen thermopile pyranometer. Originally recorded using a Campbell-Stokes sunshine recorder. The sun's rays are focused onto a card (treated to prevent it from catching fire) and the brown scorch mark on the card is then measured. The cards are of varying lengths applicable to the time of year (winter, equinox, and summer).

Radiation

RAD J/cm2 Total solar radiation 1931-current date

Total over 24 hours, 0000GMT to 2400GMT

Total solar radiation measured since 2004 by a CM3 Kipp and Zonen thermopile pyranometer. Recorded since 1921, but the data in e-RA are from 1931, as the early data was considered unreliable. Originally recorded with a Callendar radiation chart recorder. In 1955 this was replaced with a Moll-type solarimeter (Kipp) with a paper chart recording potentiometer. Daily totals were obtained by planimeter integration until 1958 when an automatic integrator was added. A Kipp integrator and recorder was used from 13th November 1975, and a Kipp and Zonen integrator installed in 1989.

All data before 1955 should be treated with caution. There was much uncertainty about the sensitivity of the equipment (Penman 1974). Radiation readings between 1947 and 1954 are around 20% higher than would be expected from sunshine hours, and much data is missing between 1947 and 1949.

Data are recorded as J/cm2. To convert to MJ/m2 divide by 100 (see Conversion factors).

Cloud

CLOUD okta Cloud cover 1915-2007

Recorded at 0900GMT

Observed cloud cover on a scale of 0 to 9 Oktas. 0 = the complete absence of cloud. 1 = a cloud amount of 1 eighth or less of the sky, but not zero, etc. 7 = a cloud amount of 7 eighths or more, but not full cloud cover. 8 = full cloud cover with no breaks. 9 = sky obscured by fog or other meteorological phenomena.

Wind

WDIR degrees Wind direction (0-360 degrees) (at 10m) 1853-current date

Recorded at 0900GMT

Wind direction (WDIR) has been recorded since 1853 and is measured by a wind vane. It is shown as an angle, going clockwise from North. 360 = North, 90 = East, 180 = South, 270 = West. The reading 0 (or 000) indicates that there is no wind, ie the windspeed is 0 m/s. A WDIR reading of 0 with a windspeed greater than 0 implies that the WDIR is 360 degrees (North).

Since 2004 it has been recorded by electronic wind vane (Vector Instruments, W200P) at a height of 12.8m above ground level. The standard height for surface wind measurements over open and level terrain is 10m. However, no correction is needed for wind measured between 8 and 13m (Met Office, 1982). We therefore assume a mid-point height of 10m. From 2004 WDIR has been calculated as an average over 10 minutes from 0850 to 0900GMT.

From 1978 (WDIR) was measured by a wind vane linked to a Munro roll chart recorder (model IM175). Previously it was estimated from a wind vane with fixed ordinal points.

WFORCE code Wind force in Beaufort scale (0-12) 1915-1959

Recorded at 0900GMT

Wind speed was first estimated using the Beaufort scale, which describes wind force on a scale of 0 (no wind) to 12 (hurricane) based on observations of the movement of smoke, leaves, branches, etc. From 1960 onwards this was replaced by direct measurements of wind speed (WINDSP).

The Beaufort scale can be converted to wind speed: V = 0.836 x SQRT (B3)

where V is the equivalent wind speed (m/s) at 10 metres above ground level and B is Beaufort scale number (see Conversion factors).

WINDSP m/s Wind speed (at 10m) 1960-current date

Recorded at 0900GMT

Direct measurement of wind speed (WINDSP) by cup anemometer replaced the visual assessment of windspeed (WFORCE) based on the Beaufort scale in 1960.

Since 2004 it has been recorded by electronic cup anemometer (Vector Instruments, A100LK/2) installed at a height of 12.8m above ground level. The standard height for surface wind measurements over open and level terrain is 10m. However, no correction is needed for wind speeds measured between 8 and 13m (Met Office, 1982). We therefore assume a mid-point height of 10m.

From November 1977 it was measured by a cup anemometer linked to a Munro roll chart recorder (model IM175). Previously it was measured with a Dines anemometer.

WINDSP and WFORCE are point values, recorded at 0900GMT. From 2004 WINDSP has been calculated as an average over 60 seconds sampled at 0900GMT.

Average daily (24 hour) windspeed can be calculated from total daily WINDRUN, correcting for height (see Conversion factors).

WINDRUN km Run of Wind (at 2m) 1946-current date

Total run of wind in 24 hours, recorded at 0900GMT

WINDRUN measures the total 'run' (distance) of wind in 24 hours. It is measured by a cup anemometer. Since February 1st 2014 it has been recorded by an electronic cup anemometer (Vector Instruments A100LK) at the standard height of 2m above ground level.

Recorded from February 4th 2004 to January 2014 with an electronic cup anemometer (Vector Instruments, A100LK/2) at 12.8m above ground level, downscaled to the 2m equivalent by multiplying by 0.78 (see Conversion factors)

From 1946 to February 3rd 2004 recorded manually using a cup anemometer with a calibrated meter at the standard height of 2m.

Diary

Daily observations, based on standard Met Office weather codes. Discontinued 1978 or mid 2007.
DYHAIL Code Code indicating type of hail 1960-1988; 1998-2007

Recorded at 0900GMT

Manual observations indicating if hail was present during the day, and if so, what type. Code 0-7. 1 = Ice prisms; 2 = Snow grains; 3 = Snow pellets; 4 = Ice pellets; 5 = Hail (5-9mm diameter); 6 = Hail (10-19mm diameter); 7 = Hail (20mm diameter or more). Null or code 0 = No Hail.

DYSNOW Code Code indicating day with snow or sleet 1960-88; 1998-2007

Recorded at 0900GMT

Manual observations recording if snow or sleet was present. Code 1 = sleet, code 5 = snow crystals. Code 0 = no snow.

DYTHUN Code Code indicating day with thunder 1960-1988; 1998-2007

Recorded at 0900GMT

Manual observations recording if thunder was present. Code 1 = thunder during the day, code 0 = no thunder during the day.

FOG Code Code indicating day with fog 1960-1978

Recorded at 0900GMT

Manual observations recording if fog was present. Code 1 = fog present, code 0 = no fog.

SNOWL Code Code indicating whether snow lying 1960-1978

Recorded at 0900GMT

Manual observations recording if snow was present. This may have been snow from a previous day. See FSNOWD for depth of freshly fallen snow for the current day. Code 1 = snow present, code 0 = no snow.

SNOWD mm Total depth of snow 1960-2007

Recorded at 0900GMT

Manual recording of total depth of lying snow at the time of observation. This may have been snow from a previous days. See FSNOWD for depth of freshly fallen snow for the current day.

FSNOWD mm Depth of freshly-fallen snow 1960-1978

Recorded at 0900GMT

Manual recording of total depth of freshly-fallen snow.

Other selected fields

RELH % Relative humidity 1925-current date

Recorded at 0900GMT

Since August 7th 2018 measured by a Relative Humidity sensor EE181 (manufactured by E+E Elektronic Corporation, supplied and calibrated by Campbell Scientific). This replaced the MP100A RH Sensor (manufactured by Rotronics, supplied by Campbell Scientific) installed in late 2013. Previously derived from WETB and DRYB (see derived variables).

BAR mb Barometric pressure 1915-1959; 1977-2003

Recorded at 0900GMT

Atmospheric pressure was measured with a mercury barometer until 2003. For further details, see Met Office (1982) p 103.

THERM °C Attached thermometer reading for barometric pressure 1915-1959

Recorded at 0900GMT

A thermometer attached to the instrument casing, known as the attached thermometer, was used to measure the temperature of the mercury column from which the density of the mercury was established. The barometer and attached thermometer were kept indoors. For further details, see Met Office (1982) p 103.

BAR_MSL mb Air pressure at Mean Sea Level (MSL) 1950-1977

Recorded at 0900GMT

Atmospheric pressure corrected to Mean Sea Level was measured with a mercury barometer. For further details, see Met Office (1982) p 103.

VAP mb Vapour pressure 1946-current date

Recorded at 0900GMT

Since January 15th 2014 derived from RELH and DRYB after the method of Buck (1981), calculated within the datalogger. Previously derived from DRYB and WETB (see derived variables).

VIS Code Visibility 1923-2007

Recorded at 0900GMT

Manual recording of visibility. Codes 0-9, E, X (1960-2007): CODE X = Dense fog. Visibility range 0-19m; CODE E = Dense fog. Visibility range 20-39m; CODE 0 = Thick fog. Visibility range 40-99m; CODE 1 = Thick fog. Visibility range 100-199m; CODE 2 = Thick fog. Visibility range 200-399m, CODE 3 = Moderate fog. Visibility range 400-999m; CODE 4 = Very poor visibility, range 1000-1999m; CODE 5 = Poor visibility, range 2000-3999m; CODE 6 = Moderate visibility, range 4-9km; CODE 7 = Good visibility, range 10-19km; CODE 8 = Very good visibility, range 20-39km; CODE 9 = Excellent visibility, range 40km or over.

Codes A-M, (1923-1959, 1960-2007 equivalent code in brackets): CODE A (E) = Dense fog. Visibility range 18-22m; CODE B (0) = Thick fog. Visibility range 36-44m; CODE C (1) = Thick fog. Visibility range 90-110m; CODE D (2) = Fog. Visibility range 180-220m; CODE E (3) = Moderate fog. Visibility range 360-440m; CODE F (4) = Very poor visibility. Visibility range 900-1100m; CODE G (5) = Poor visibility. Visibility range 1.8-2.2 km; CODE H (6) = Moderate visibility. Visibility range 3.6-4.4km; CODE I (6) = Moderate visibility. Visibility range 6.3-7.7 km; CODE J (7) = Good visibility. Visibility range 9-11 km; CODE K (8) = Very good visibility. Visibility range 18-22km; CODE L (8) = Very good visibility. Visibility range 27-33km CODE M (9) = Excellent visibility. Visibility range 36-44km.

Datasets available

Annual Mean Air Temperature Anomaly at Rothamsted 1878-2019
Meteorological dataset Rothamsted has one of the longest running continuous sets of daily meteorological recordings in the world. Temperature has been measured since 1878. The figure above shows the temperature anomaly in annual mean air temperature (black circles), for years 1878 to 2019, relative to the 1878 to 1920 long-term average, which represents the pre-industrial era.
RMAAtempanom
Annual Mean Air Temperature at Rothamsted 1878-2019
Meteorological dataset Rothamsted has one of the longest running continuous sets of meteorological recordings in the world. The figure shows the annual mean air temperature at Rothamsted every year from 1878-2019. Also shown is the mean over each five-year period, 1878-1882, 1883-1887, etc.
RMAAtemp
Mean Monthly Rainfall at Rothamsted March 1853 - July 2018
Meteorological dataset This dataset represents the monthly mean rainfall at Rothamsted continuously from March 1853 - July 2018 and is based on continuous daily records measured at the site.
RMMRAINS5318
Mean monthly temperature at Rothamsted October 1985-September 2017
Meteorological dataset This dataset represents the mean monthly temperature at Rothamsted from October 1985 - September 2017 and is based on continuous daily records measured at the site.
rmsMMT10850917
Rothamsted 30-year mean meteorological data 1961-1990
Meteorological dataset This dataset consists of the 30-year monthly mean meteorological data measured at Rothamsted Research, Harpenden, UK, from January 1961 until December 1990.
R30YrMeans6190
Rothamsted 30-year mean meteorological data 1971-2000
Meteorological dataset This dataset consists of the 30-year monthly mean meteorological data measured at Rothamsted Research, Harpenden, UK, from January 1971 until December 2000.
R30YrMeans7100
Rothamsted 30-year mean meteorological data 1981-2010
Meteorological dataset This dataset consists of the 30-year monthly mean meteorological data measured at Rothamsted Research, Harpenden, UK, from January 1981 until December 2010.
R30YrMeans8110
Rothamsted 30-year mean meteorological data 1991-2020
Meteorological dataset This dataset consists of the 30-year monthly mean meteorological data measured at Rothamsted Research, Harpenden, UK, from January 1991 until December 2020.
R30YrMeans9120
Annual Mean Air Temperature at Rothamsted 1878-2013
Meteorological dataset Rothamsted has one of the longest running continuous sets of meteorological recordings in the world. The figure shows the annual mean air temperature at Rothamsted every year from 1878-2013. Also shown is the mean over each five-year period, 1878-1882, 1883-1887, etc.
RMAAtemp
Mean monthly rainfall at Rothamsted October 1985-September 2017
Meteorological dataset This dataset represents the mean monthly rainfall recorded at Rothamsted from October 1985 - September 2017 and is derived from continuous daily records measured at the site.
rmsMMR10850917
Additional data is available through e-RAdata. Please register for access.

Rothamsted Met Data Monthly & Annual Summaries

September 2021: The month of September was warm and dull with below average rainfall.

Rainfall was 54.1 mm, which is 3.60 mm below average. We had 11 days with 0.2 mm or more of rain and 4 days with over 5 mm. The most was 24.2 mm on the 28th.

The mean maximum The mean maximum and minimum temperatures were above average at 20.6 ºC (+2.08 ºC) and 11.5 ºC (+1.32 ºC) respectively. The highest (daytime) temperature was 27.9 ºC on the 7th. The lowest (night) temperature was 4.6 ºC on the 30th.

Sunshine was 136.2 hrs which is 14.46 hrs below average. There was 1 day without sunshine and the most recorded was 11.7 hours on the 7th.

There were no frosts.

Note: The average refers to the 30 year means 1991-2020.

August 2021: August was cool, dry and dull with below average temperature, rainfall and sunshine.

Rainfall was below average with 37.0 mm (-34.99 mm). We had 13 days with 0.2 mm or more of rain, of which 3 days had more than 5.0 mm; the most was 16.8 mm on the 21st.

The mean maximum air temperature was below average with 19.9 ºC (-1.69 ºC) and the mean minimum air temperature was just above average with 12.3 ºC (+0.02 ºC). The highest temperature was 23.3 ºC on the 14th. The lowest temperature was 8.1 ºC on the 29th.

Sunshine was below average with 114.2 hours (-75.21 hours). There were two days without sun and the sunniest day was the 4th with 9.4 hours.

There were no frosts.

Note: The average refers to the 30 year means 1991-2020.

July 2021: July 2021 was warm, relatively dry and dull.

Rainfall was 51.0 mm, which is 4.46 mm below average. We had 17 days with 0.2 mm or more of rain with 2 days having more than 5 mm. The greatest rainfall was 21.4 mm recorded on the 5th.

Sunshine was below average with 195.6 hrs (-11.18 hours). The most was 14.4 hours on the 16th and there was 0 days where no sunshine was recorded.

The average maximum air temperature was 22.3 ºC (+0.29 ºC) and the average minimum air temperature was 13.4 ºC (+1.04 ºC). The warmest day reached 29.5 ºC on the 20th. The lowest minimum air temperature was 10.0 ºC on the 16th.

There were no frosts.

Note: The average refers to the 30 year means 1991-2020.


June 2021: June 2021 was warm, wet and relatively cloudy.

Rainfall was 77.6 mm, which is 22.78 mm above average. We had 11 days with 0.2 mm or more of rain, of which 5 days had more than 5.0 mm. The most rainfall in a single day was 23.6 mm collected on the 18th.

Sunshine was 184.7 hours, which is 21.09 below average.

The mean maximum and minimum temperatures were both above average with 20.3ºC (+0.77ºC) and 11.8 ºC (+1.62ºC) respectively. The hottest day reached 26.2ºC on the 13th. The coolest night dropped to 5.1ºC on the 23rd. The June 2021 average air temperature was the 8th warmest in our records (started 1878).

There were no frosts.

Note: The average refers to the 30 year means 1991-2020.


May 2021: May was a cold, dull and wet month with below average temperatures and sunshine hours, and above average rainfall.

Rainfall was 94.4 mm, which is 41.14 mm above average. We had 24 days with 0.2 mm or more of rain, of which 9 days had more than 1.0 mm. The greatest fall of rain was 11.2 mm on the 21st of May.

Sunshine was below average with 150.4 hrs. (-52.92 hrs); the most was 10.1 hours on the 31st. There was one day without sunshine.

The average maximum and minimum temperatures were below average at 14.7ºC (-1.78ºC) and 6.2ºC (-1.10ºC). The highest (max) temperature was 22.3 ºC on the 31st and the lowest (min) temperature was 0.2ºC on the night of the 6th.

We had 0 air frosts and 10 ground frosts.

Note: The average refers to the 30 year means 1991-2020.


April 2021: April was sunny, cold, and mainly dry.

Rainfall was 1.6 mm which is 52.40 mm below average. We had 4 days with 0.2 mm or more of rain. The wettest day was the 9th with 1.0 mm. April was the driest since records began in 1853.

Sunshine was above average with 215.8 hours (+43.79 hours); the most was 12.9 hours on the 22nd and there was only 1 day without sunshine.

The average maximum and minimum temperatures were below average at 11.5ºC (-1.84ºC) and 1.1ºC (-3.36ºC). The warmest day was the 19th which reached 16.2ºC, and the coldest night was on the 7th when it dropped to -3.0ºC.

We had 11 air frosts and 22 ground frosts.

Note: The average refers to the 30 year means 1991-2020.


March 2021: March was relatively warm and cloudy with below average rainfall.

Rainfall was below average with 27.6 mm recorded, (-19.47 mm). We had 13 days with 0.2 mm or more of rain, and 1 day with more than 5 mm. The most recorded was 5.0 mm on the 10th.

Sunshine was below average with 112.0 hrs (-16.36); the most recorded was 10.9 hours on the 30th. There were 2 days without sunshine.

The mean maximum and minimum temperatures were above average with 10.7ºC (+0.42) and 3.5ºC (+0.62) respectively. The highest maximum temperature was 22.5ºC on the 30th and the lowest minimum was -1ºC on the 6th.

We had 1 air frost and 18 ground frosts.

Note: The average refers to the 30 year means 1991-2020.


February 2021: February was warm with below average sunshine and rain with some snow.

Rainfall was below average with 45.8 mm (-11.15 mm). We had 15 days with over 0.2 mm, and 4 days with more than 5.0 mm. The greatest rainfall was 9.0 mm on the 4th. Precipitation fell as snow on 8th with a very slight flurry on afternoon of 10th.

Sunshine was below average with 80.8 hrs. (-5.38 hrs). We had 3 days without any sunshine and the most was 9.1 hrs on the 26th.

The mean maximum and the mean minimum temperatures were above average with 8.1 ºC (+0.56ºC) and 2.2ºC (+0.73ºC) respectively. The lowest minimum was -4.9ºC on the 11th, and the highest maximum was 16.0ºC on the 24th.

We had 8 air frosts and 14 ground frosts.

Note: The average refers to the 30 year means 1991-2020.


January 2021: January was cold, wet and had below average sunshine.

Rainfall was above average with 113.6 mm (+39.48 mm). We had 23 days with 0.2 mm or more of rain and 10 had more than 5.0 mm. The most on one day was 25.6 mm on the 13th. Snow fell and settled on 24th.

Sunshine was below average with 52.0 hours (-11.91 hours); the most was 7.0 hours on the 25th. We had 9 days with no sunshine.

January’s mean maximum and minimum temperatures were below average at 5.8ºC (-1.20ºC) and 0.4ºC (-1.22ºC) respectively. The highest day temperature was 11.7ºC on the 28th and the lowest minimum was -4.9ºC on the 25th.

We had 17 air frosts and 18 ground frosts.

Note: The average refers to the 30 year means 1991-2020.


Previous Years

Key References

2021

  • Addy, J. W. G. , Ellis, R. H. , Macdonald, A. J. , Semenov, M. A. and Mead, A. (2021) "The impact of weather and increased atmospheric CO2 from 1892 to 2016 on simulated yields of UK wheat", J. R. Soc. Interface, 18, 20210250
    DOI: 10.1098/rsif.2021.0250

2020

  • Addy, J. W. G. , Ellis, R. H. , Macdonald, A. J. , Semenov, M. A. and Mead, A. (2020) "Investigating the effects of inter-annual weather variation (1968-2016) on the functional response of cereal grain yield to applied nitrogen, using data from the Rothamsted Long-Term Experiments", Agricultural and Forest Meteorology, 284, 107898
    DOI: 10.1016/j.agrformet.2019.107898

2018

  • Macdonald, A. , Poulton, P. , Clark, I. , Scott, T. , Glendining, M. , Perryman, S. , Storkey, J. , Bell, J. , Shield, I. , Mcmillan, V. and Hawkins, J. (2018) "Guide to the Classical and Other Long-term experiments, Datasets and Sample Archive. Rothamsted Research"
    DOI: 10.23637/ROTHAMSTED-LONG-TERM-EXPERIMENTS-GUIDE-2018

2015

1974

For further information and assistance, please contact the e-RA curators, Sarah Perryman and Margaret Glendining using the e-RA email address: era@rothamsted.ac.uk