Extreme weather recordings

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Extreme weather at Rothamsted

Last updated 4th July 2025.

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, 2018 and 2022, 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

Hottest day

The highest temperature at Rothamsted (Harpenden), since records began in January 1878, was 38.4 C on Tuesday 19th July 2022 (this beats the previous record at Harpenden of 36.7 °C on July 25th 2019). July 19th 2022 was also the record hottest day at the Rothamsted weather stations at Woburn in Bedfordshire, with 39.5 °C, and at Brooms Barn in Suffolk, with 38.8 °C.

The 2022 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 of 40.3 C at Coningsby in Lincolnshire - the first time 40C has been exceeded in the UK since records began (surpassing the previous record of 38.7 °C in Cambridge on 25th July 2019).

Coldest day

The lowest temperature, since records began in January 1878, was -17.0 °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).

Original record sheet relating to the coldest day

Wettest day

The wettest day, since records began in February 1853, with 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 the wettest day

The ten warmest days since records began in January 1878.

The ten warmest days (maximum temperature reached in that day) at Rothamsted have all been since 1990, nine of them in the 21st century.

Rank
Date
Temperature °C
1
19th July 2022
38.4
2
25th July 2019
36.7
3
18th July 2022
35.7
4
10th August 2003
35.6
5
31st July 2020
34.6
6
6th August 2003
34.2
7
7th August 2020
33.8
8
3rd August 1990
33.8
9
9th August 2003
33.8
10
1st July 2015
33.4

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 °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

Extreme months

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

Its getting warmer....
Eight of the warmest months were since 2000, whilst none of the coldest months was after 2000.The highest maximum mean monthly temperature ever recorded was July 2006 and the coldest minimum mean month ever recorded was February 1947.

Highest mean maxiumum monthly temperature
Year
Lowest mean minimum monthly temperature
Year
Highest mean average monthly temperature
Year
Lowest mean average monthly temperature
Year
January
9.5
2007
-6.1
1963
12.5
2008
-10.3
1963
February
10.9
2019
-6.3
1895
13.7
2024
-10.3
1895
March
14.1
1938
-2.0
1883
15.6
1968
-5.6
1965
April
17.6
2011
0.4
1917
17.7
1945
-0.9
1917
May
19.0
1947
4.0
1879
22.0
1922
3.1
1981
June
23.7
1976
7.2
1916
25.3
1976
6.6
1991
July
26.1
2006
9.4
1907
28.3
2022
8.5
1888
August
25.2
2022
9.2
1885
26.4
2020
8.9
1912
September
22.5
2023
6.3
1986
24.2
1949
4.7
1885
October
17.7
1921
2.4
1888
20.0
2011
-0.2
1895
November
12.4
2011
-0.8
1910
16.1
1938
-5.6
1923
December
12.5
2015
-4.3
1890
13.2
2015
-8.5
1891

Bold indicates a record in the last year.

The wettest and driest months since records began in January 1853.

Its getting more rainy....
Half of the wettest months were since 2000. The driest months were all before 1990, with the exception of April 2021, five of the driest were in the 19th Century.

Highest Total Rainfall
Year
Lowest Total Rainfall
Year
January
176.3
2014
8.1
1855
February
141.8
2014
0.9
1891
March
129.2
1979
1.1
1929
April
168.7
2012
1.6
2021
May
135.8
2007
1.5
1990
June
166.4
2012
2.5
1925
July
167.2
1855
4.1
1921
August
172.0
2020
1.7
1947
September
194.5
1896
0.9
1865
October
198.7
1987
1.1
1947
November
192.4
1940
4.0
1867
December
190.9
1914
4.7
1853

The sunniest and dullest months since records began in January 1890.

Its getting more sunny...
The sunniest months are spread evenly across the 125 years, The cloudiest months have been before 1997..

Highest Total Sunshine Hours
Year
Lowest Total Sunshine Hours
Year
January
91.1
1984
22.2
1996
February
145.5
2008
22.5
1940
March
205.7
1907
45.2
1984
April
270.1
1893
84.7
1966
May
308.9
2020
116.9
1981
June
289.1
1975
115.2
1909
July
314.9
1911
90.8
1965
August
279.7
1995
75.8
1894
September
228.7
1895
32.6
1894
October
163.9
1997
46.3
1976
November
113.1
1989
26.5
1962
December
94.8
2014
6.1
1890

See Rothamsted Highs and Lows for complete records of variables and extreme months (temporarily unavailable since July 2025 due to server issues).

 

Extreme Years

Temperature extremes, since records began in January 1878.

The ten warmest years

At Rothamsted, the ten warmest "mean annual average" years have all occurred since 2002.

The warmest 'average annual temperature' years were 2014 and 2022 with mean annual temperatures of 11.2 °C (the annual average is 10.23 °C).

 

Rank
Year
Mean annual average temperature °C
1
2014
11.24
2
2022
11.23
3
2023
11.11
4
2020
11.09
5
2024
11.00
6
2006
10.88
7
2011
10.84
8
2018
10.79
9
2002
10.63
10
2017
10.62

At Rothamsted, seven of the warmest "mean annual maximum" temperature years have occurred since 2000, but two were before 1950 (1921 and 1950):

Rank
Year
Mean annual maximum temperature degrees C
1
2022
15.52
2
2020
15.15
3
2023
15.11
4
2014
15.10
5
2003
14.90
6
2018
14.89
7
2011
14.74
8
1949
14.74
9
1921
14.70
10
1989
14.67

 

The ten coldest years

At Rothamsted, the ten coldest 'average annual temperature' years have all occurred before 1964, half of them were in the 19th Century. The coldest year was 1879 with a mean annual temperature of 7.3 °C.

Rank
Year
Mean annual average temperature degrees C
1
1879
7.27
2
1963
7.94
3
1892
8.04
4
1887
8.11
5
1888
8.11
6
1919
8.12
7
1917
8.14
8
1962
8.19
9
1922
8.36
10
1886
8.45

At Rothamsted, the ten coldest 'minimum annual temperature' years have also all occurred before 1964, seven of them were in the 19th Century. The coldest year was 1887 with a mean annual temperature of 3.7 °C.

Rank
Year
Mean annual minimum temperature degrees C
1
1887
3.73
2
1879
3.75
3
1892
3.79
4
1963
4.08
5
1962
4.21
6
1919
4.22
7
1895
4.25
8
1891
4.31
9
1890
4.36
10
1888
4.37

 

Rainfall extremes, since records began in February 1853.

Years are getting wetter..

The wettest year was 2012 with 1059.2mm total rainfall, the second wettest year was 2020 with 1032.8mm total rainfall.

The driest year was 1921 with 380.1mm total rainfall.

Rank - Highest
Year
Total rainfall (mm)
1
2012
1059.4
2
2020
1032.8
3
2024
991.6
4
2000
973.5
5
1903
948.8
6
2014
925.7
7
1879
916.5
8
1993
888.3
9
1875
887.7
10
1912
886.6
Rank - Lowest
Year
Total rainfall (mm)
1
1921
380.1
2
1854
396.8
3
1864
410.4
4
1933
430.3
5
1858
434.9
6
1898
488.8
7
1870
501.3
8
1887
504.8
9
1861
506.1
10
1902
511.1

 

Sunshine extremes, since records began in 1893.

Years are getting sunnier...

Sunniest Years

Seven of the sunniest years were since 1988, four of them since 2000. The sunniest year was 2022 with 1912.50 total sun hours:

Rank
Year
Total hours of sunshine in year
1
2022
1912.8
2
1989
1867.6
3
2018
1865.6
4
2003
1858.3
5
1929
1853.8
6
1995
1853.3
7
1893
1840.4
8
1990
1839.9
9
1906
1825.0
10
2020
1801.2

Cloudiest Years

The top ten cloudiest years were all prior to 1981, half of them were in the 1950s/60's. The cloudiest year was 1968 with 1149.2 total sun hours:

Rank
Year
Total hours of sunshine in year
1
1968
1149.2
2
1966
1274.7
3
1894
1277.4
4
1937
1278.1
5
1981
1286.3
6
1963
1288.4
7
1936
1292.8
8
1954
1303.0
9
1965
1317.3
10
1958
1324.0

 

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

Extreme Decades

Temperature extremes, averaged over decades, since records began in January 1878.

The last decade 2010-2019 had the warmest maximum daily average temperature ever recorded at Rothamsted since records began fourteen decades ago.

The decade with the warmest maximum daily average temperature (23.74°C) was 2010-2019

The decade with the coolest maximum daily average temperature (20.66°C) was 1960-1969

The decade with the warmest mean annual average temperature (10.38°CC) was 2000-2009

The decade with the coolest mean annual average temperature (8.67°C) was 1880-1889

The decade with the warmest minimum daily average temperature (-2.24°C) was 2000-2009

The decade with the coolest minimum daily average temperature (-5.79°C) was 1890-1899

Decade Maximum Daily Average Temperature Mean Annual Average Temperature Minimum Daily Average Temperature
1880-1889 20.92 8.67 -5.18
1890-1899 20.78 9.06 -5.79
1900-1909 21.24 9.00 -4.08
1910-1919 21.31 9.20 -3.17
1920-1929 21.41 9.04 -4.56
1930-1939 22.01 9.27 -3.45
1940-1949 22.72 9.38 -5.27
1950-1959 21.59 9.24 -4.26
1960-1969 20.66 8.97 -5.20
1970-1979 21.18 9.27 -3.59
1980-1989 21.42 9.24 -4.52
1990-1999 22.06 9.95 -2.99
2000-2009 22.88 10.38 -2.24
2010-2019 23.74 10.31 -2.70

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.

This extremes data page is created and maintained by Sarah Perryman and Tony Scott.

If you would like to access the daily records from the e- RA database, please fill in a request form.

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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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