e-RA: the electronic Rothamsted Archive

Annual Mean Air Temperature Anomaly at Rothamsted 1878-2019

Publication date V1 1878-2019 30/07/2020

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 Anomaly 1878-2019. Electronic Rothamsted Archive https://doi.org/10.23637/rms-RMAAtempanomaly-1.

Click to download chart Annual Mean Rothamsted Temperature Anomaly

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 Anomaly 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 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. Variation in annual temperature is smoothed using an 11-year (132 month) moving average (red line, which removes solar variability and shorter-term variability such as the Southern Oscillation (Hansen et. al., 2010). The figure shows that air temperatures have risen sharply since 1987 (Scott, 2015) with annual temperatures, over the last decade, estimated to be between 1.3°C and 1.6°C higher than the pre-industrial period (Hansen. & Sato, 2016). Much of the rise is due to increases in temperature during the autumn and winter months, and at night-time.

This data is related to the Annual Mean Air Temperature at Rothamsted 1878-2019  but based on monthly anomaly data rather than annual temperature data.


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 originally recorded using a mercur-in-glass with indicator bar minimum thermometer and Tmin using a spirit-in-glass with indicator bar minimum thermometer, both housed in a naturally aspiring temperature screen.

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

Data calculations

For each month the mean air temperature is determined from daily data, also the annual mean air temperature for each year (1878 to 2019). The long-term monthly average and annual average for 1878 to 1920 is also determined. The annual mean temperature anomaly and 132 month (11 year) moving average is determined from these annual and monthly air temperature data using Excel functions.


Meteorological station
Weather data
Air temperature
Climate change
Global warming

Further Information

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

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

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

The above graph is based on ‘A Better Graph’ (a Communication by Hansen and Sato, 2016 http://www.columbia.edu/~jeh1/mailings/2016/20160926_BetterGraph.pdf).

Further details can be obtained from the e-RA curators and the Key References below.

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Key References








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