e-RA: the electronic Rothamsted Archive

Rothamsted 30-year means 1991-2020

The Data

Rothamsted 30-year mean meteorological data 1991-2020

30 year means 1991-2020

Download the Data

This dataset is presented as a downloadable Excel Spreadsheet:

Rothamsted 30-year meteorological means 1991-2020.xlsx

and as comma-separated values (CSV):

Rothamsted 30-year meteorological means 1991-2020.csv

Publication Date

Publication date V1. 2021/01/21
Last updated V1. 2021/01/21

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 30-year meteorological means 1991-2020. Electronic Rothamsted Archive https://doi.org/10.23637/OARES30YrMeans9120

Rothamsted relies on the integrity of users to ensure that Rothamsted Research receives suitable acknowledgement as being the originators of these data. This enables us to monitor the use of each dataset and to demonstrate their value. Please send us a link to any publication that uses this Rothamsted data.


This dataset consists of the 30-year monthly mean meteorological data measured at Rothamsted Research, Harpenden, UK, from January 1991 until December 2020, and is derived from daily measurements taken at the site. Thirty years is chosen as a period long enough to eliminate year-to-year variations. This dataset continues the 1981-2010 dataset.


  • Rain: The mean total monthly rainfall including all precipitation (snow, rain, mist and fog) captured in a 5 inch rain gauge (mm per month)
  • Sunshine: The mean total hours of sunshine (hours per month)
  • Maximum temperature: The mean maximum monthly air temperature (degrees C)
  • Minimum temperature: The mean minumum monthly air temperature (degrees C)
  • Average temperature: The mean of the maximum and minimum air temperature (degrees C)
  • Soil temperature under grass 30cm: The mean monthly soil temperature under grass at 30cm depth, measured at 0900 GMT (degrees C)
  • Soil temperature under grass 100cm: The mean monthly soil temperature under grass at 100cm depth, measured at 0900 GMT (degrees C)
  • Wind: The mean monthly wind speed measured at 2 metres above ground level, averaged over 24 hours (km per hour)
  • Evaporation: The mean total monthly evaporation over two open water tanks installed in the spring of each year (mm per month)
  • Radiation: The mean daily solar radiation measured with a Kipp Solarimeter (J/cm2)

    Rothamsted Research, Harpenden, Herts, UK. 51.8067 N 0.3602 W 128 m asl.

    Provenance & Quality

    This 30-year mean meteorological data contained in this spreadsheet are derived from daily data measured at Rothamsted Research, Harpenden, Herts, UK. Mean monthly data is determined from daily data using Genstat 19th Edition. Missing values are acquired from the Met Office Station on site. Verification of daily data includes checks for instrument errors, for missing data and outliers. The original raw daily data is available, after registering, from the e-RA database. Please contact the e-RA Curators for an access password and further details.

    Supporting Information

    These data are displayed in charts on the following page of the e-RA website: 30-year mean weather charts.

    Further information is available on the e-RA met web pages and the Rothamsted Guide to the Long-Term Experiments (Macdonald et. al. 2018) (DOI: 10.23637/Rothamsted Guide to the Long-Term Experiments) page 45.


    Air temperature
    Climate change
    Meteorological station
    Weather data
    Meteorological factors
    Soil temperature
    Wind speed
    Rainfall patterns
    Rothamsted Research


    Tony Scott, Chris Hall, Sarah Perryman, Margaret Glendining.


    Rothamsted Research.

    Further Information and contact details

    Please contact the e-RA Curators for further information, and assistance with questions about the data or its interpretation:

    e-RA Curators,
    Department of Computational and Analytical Sciences (CAS)
    Rothamsted Research
    Harpenden, Herts, AL5 2JQ

    email: era@rothamsted.ac.uk


    The Long-term Experiments and weather stations are supported by the Lawes Agricultural Trust and BBSRC National Capability Funding (BBS/E/C/000J0300) recognising the national and international importance of the data.

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