e-RA: the electronic Rothamsted Archive

Annual Mean Air Temperature at Rothamsted 1878-2019

Publication date V1 1878-2013 21/04/2017

Last updated V2 1878-2019 06/02/2020

Access Use and Conditions

Creative Commons License This work is licensed under a Creative Commons Attribution 4.0 International License.

YOU MUST CITE AS: Rothamsted Research (2020). Rothamsted Mean Long-Term Annual Temperature 1878-2019. Electronic Rothamsted Archive https://doi.org/10.23637/rms-RMAAtemp-02.

Click to download chart Annual mean Rothamsted temperature

Click the chart above for a PDF version. Summary data used for this chart are derived from annual daily data measured at Rothamsted Meteorological Station and are available to download as an Excel Spreadsheet: Annual Mean Rothamsted Temperature 1878-2019.

The original raw data is available, after registering, from the e-RA database. Please contact the e-RA Curators for a password and further details.


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 (white circles). Also shown is the mean over each five-year period, 1878-1882, 1883-1887, etc (filled circles). The red line shows the mean temperature, 1878-1987. Mean annual air temperature has fluctuated considerably between 1878-2019. However, when the variation in annual temperature is smoothed using an 11-year (132 month) moving average (green dashed-line), it is apparent that air temperatures have risen sharply since 1987 (Scott, 2015). An 11-year moving average removes solar variability and shorter-term variability such as the Southern Oscillation (Hansen et. al., 2010). The mean air temperature at Rothamsted in 2019 was 10.48°C which is 1.42°C higher than the 1878-1987 average of 9.06°C. The warmest year on record was 2014 with a mean annual temperature of 11.23°C. The 10 warmest years on record occurred in the last 20 years. Much of the rise is due to increases in the autumn and winter months, and in night time temperatures.


This annual data, 1878-2019, is plotted visually with each years' temperature represented by a coloured line going from deep blue (coldest) to deep red (hottest) in relation to the long-term mean (white). The deeper the red, the higher the temperature the darker the blue the colder the temperature. The recent steep increase in temperature since the late 1980s is illustrated by the concentration of red stripes to the right-hand side (visualisation concept created by Professor Ed Hawkins, University of Reading).

Click to download chart Annual mean Rothamsted temperature


The mean daily temperature is measured over a 24 hour period 0900 to 0900 GMT and calculated from the daily maximum (Tmax) and minimum temperatures (Tmin); the mean daily tamperature = (Tmax = Tmin)/2.

First recorded in 1878, Tmax was then measured using a mercury column thermometer and Tmin using a spirit-in-glass with indicator bar minimum thermometer.

Since 2004, temperatures have been recorded automatically by thermistors (electronic temperature probes, Campbell Scientific, Type 107).


Meteorological station
Weather data
Air temperature
Climate change

Further Information

This version 2 supercedes version 1 (1878-2013).

Updated from Scott (2015) see Key References below.

For further information about the measurement of temperature at Rothamsted see Temperature.

For further information about extreme temperature records at Rothamsted see Extremes.

Further details can be obtained from the e-RA curators, the Rothamsted Guide to the Long-Term Experiments (Macdonald et. al. 2018) , p 45, and the Key References below.

Hansen, J., Ruedy, R., Sato, M. & Lo K., 2010: Global Surface Temperature Change. Rev. Geophys., 48, RG4004, doi:10.1029/2010RG000345.

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Key References








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