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e-RA: the electronic Rothamsted Archive
Rothamsted

Extreme Weather Events at Rothamsted

Last updated 29th July 2019.

Rothamsted Research at Harpenden has the longest run of freely-available daily weather data in England and has been sending returns to the UK Meteorological Office since at least 1878. In 2017, Rothamsted was recognised by the World Meteorological Organization (WMO) as a Centennial Observation Station being one of the relatively small number of sites in the UK that has been recording reliable observations continuously for more than 100 years. Rainfall has been measured daily for more than 160 years, since 1853, using a 5-inch gauge and a much larger, and unusual, 1,000th of an acre gauge. Subsequently, other weather variables were added to the list including temperature from about 1878, sunshine hours from 1890, and wind force/speed from 1915. Weather variables were recorded manually until the end of 2003; an automatic data logger was installed to record the data electronically from 1st January 2004*.

The Rothamsted weather records reflect many of the memorable national weather events such as the heatwaves of 1976 and 2018, the severe winters of 1947 and 1963, the heavy rainfall of December 2015, and the drought of 1921. The highs and lows include:

  • Extreme days
  • Extreme months
  • Extreme years

    Extreme Days

    Hottest day

    The highest temperature at Rothamsted (Harpenden), since records began in January 1878, was 36.7 degrees C on July 25th 2019. This beats the previous record of 35.6 degrees C on 10th August 2003. July 25th 2019 was also the hottest day at Woburn in Bedfordshire, with 37.5 degrees C, and at Brooms Barn in Suffolk, with 36.6 degrees C, both beating previous records on 10th August 2003.

    The 2003 European heat wave led to the hottest summer on record in Europe since at least 1540. Several weather records were broken in the United Kingdom, including the UK's highest recorded temperature 38.5 degrees C (101.3 degrees F) at Faversham in Kent on 10th August (Wikipedia).

    Coldest day

    The lowest temperature, since records began in January 1878, was -17.0 degrees C on 13th December 1981.

    The winter of 1981-82 in the United Kingdom was called "The Big Snow of 1982" by the press (Wikipedia).

    Wettest day

    The wettest day, since records began in February 1853, with 3.238 inches (82.2mm) rain was 26th June 1888.

    The Times reported on July 12 1888: “Extraordinary weather for the time of year is reported from various parts of the country" with snow in the summer!

    Original record sheets relating to these extreme daily records;

    Hottest day
    Wettest day
    Coldest day

     

    The ten warmest days
    since records began in January 1878.

    The ten warmest days (maximum temperatures) span more than 100 years at Rothamsted, from 1911, but more than half of them were post-2000.

    Rank
    Date
    Temperature degrees C
    1
    25th July 2019
    36.7
    2
    10th August 2003
    35.6
    3
    6th August 2003
    34.2
    = 4
    3rd August 1990
    33.8
    = 4
    9th August 2003
    33.8
    6
    9th August 1911
    33.5
    7
    1st July 2015
    33.4
    8
    19th August 1932
    33.3
    9
    19th July 2006
    33.1
    10
    26th June 1976
    33.0

     

    The ten coldest days
    since records began in January 1878.

    The ten coldest days (minimum temperatures) at Rothamsted were all pre-1982, with more than half of them pre-1900.

    Rank
    Date
    Temperature degrees C
    1
    13th December 1981
    -17.0
    2
    23rd January 1963
    -16.7
    3
    7th February 1895
    -16.4
    4
    8th February 1895
    -15.8
    = 5
    17th January 1926
    -15.6
    = 5
    24th January 1963
    -15.6
    7
    24th February 1947
    -15.3
    8
    21st January 1881
    -15.0
    9
    7th December 1879
    -14.9
    = 10
    8th January 1886
    -14.4
    = 10
    10th February 1895
    -14.4

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    Extreme months

     

    The hottest and coldest months since records began in January 1878.

    Half of the warmest months were since 2000, whilst ten of the coldest months were over 100 years ago.

    Highest Mean Temperature
    Year
    Lowest Mean Temperature
    Year
    January
    9.5
    2007
    -6.1
    1963
    February
    10.9
    2019
    -6.3
    1895
    March
    14.1
    1938
    -2.0
    1883
    April
    17.6
    2011
    0.4
    1917
    May
    19.0
    1947
    4.0
    1879
    June
    23.7
    1976
    7.2
    1916
    July
    26.1
    2006
    9.4
    1907
    August
    25.0
    1995
    9.2
    1885
    September
    22.2
    1929
    6.3
    1986
    October
    17.7
    1921
    2.5
    1919
    November
    12.4
    2011
    -0.8
    1910
    December
    12.5
    2015
    -4.3
    1890

    See Rothamsted Highs and Lows for complete records of variables and extreme months.

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    Extreme Years

    Temperature extremes, since records began in January 1878.

    The warmest year was 2014 with a mean annual temperature of 11.2 degrees C.

    The coldest year was 1879 with a mean annual temperature of 7.3 degrees C.

     

    Rainfall extremes, since records began in February 1853.

    The wettest year was 2012 with 1059.2mm total rainfall.

    The driest year was 1921 with 380.1mm total rainfall.

     

    Sunshine extremes, since records began in September 1890.

    The sunniest year was 1989 with 1872.3 total sun hours.

    The cloudiest year was 1968 with 1149.2 total sun hours.

     

    The ten warmest years

    At Rothamsted, the ten warmest years have all occurred since 1999.

    Rank
    Year
    Mean annual temperature degrees C
    1
    2014
    11.23
    2
    2006
    10.89
    3
    2011
    10.84
    4
    2018
    10.79
    5
    2002
    10.64
    6
    2017
    10.62
    7
    2003
    10.56
    8
    1999
    10.52
    9
    2007
    10.49
    10
    2015
    10.46

    See Rothamsted Highs and Lows for complete records of variables and extreme months.

    See Open Access data for mean annual air temperature.

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    Note: Even earlier records, in the form of a weather diary (as opposed to actual measurements), were made by Sir John Wittewronge, an ancestor of Sir John Lawes who also lived at Rothamsted Manor. These weather records provide a fascinating insight into weather conditions over five years at the end of the 17th Century (1684-1689) and give an indication of the weather experienced in Hertfordshire at a time when the Little Ice Age was affecting Europe ("'Observations of Weather' The Weather Diary of Sir John Wittewronge of Rothamsted 1684-1689". Edited by Margaret Harcourt Williams and John Stevenson and published in 1999 by Hertfordshire Record Society Publications).

    *Some variables such as snow and cloud cover continued to be measured manually until May 2007. These trained observers who kept records before automation included Chris Hall, Arthur Day, John Croft, Dave Yeoman, Bob Norrish, Gavin Harrison, Helen Stevenson, Paul Hargreaves, Tim Hall, Edwin Grey and the first recorder, Thomas Wilson. The current weather recorder is Tony Scott.


    Contact the e-RA Curators to arrange a password to download raw data from the database.


    News & Links:

    Annual Mean Air Temperature at Rothamsted (1878-2013) e-RA Open Access data

    World Meteorological Centennial Observing Stations WMO 2017

    Centennial Recognition for 'Memories of Weather' Met Office December 2018

    Major Contribution to Climate Science Recognised Rothamsted Research News December 2018

    Rothamsted Research to be commemorated by the World Meteorological Organisation ITV News March 2019

    WMO confrims past 4 years were warmest on record WMO February 2019

    Met Office Weather Observations Website WOW

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