UK climate averages for 1981-2010
Summary of key features
- The Met Office maintains long-term averages of the UK climate, based on standard 30-year periods, following World Meteorological Organization (WMO) recommendations. Long-term averages for the latest 30-year period 1981-2010 have been produced as an update to the existing 1971-2000 and 1961-1990 averages. This is in line with most other countries.
- Differences between the 1981-2010 averages and those for 1971-2000 reflect the fact that the years 2001 to 2010 are included in the averages, whereas the years 1971 to 1980 are omitted. The 1981-2010 averages therefore better reflect the current climate of the UK than averages for earlier periods.
- Differences in the averages can help provide an indication of the ways in which the UK's climate has changed over recent decades.
- From July 2012, the Climate summaries for the UK will report the anomaly value (the difference from or percentage of average) using the 1981-2010 period. In the summaries from January 2011 onward, the 1971-2000 anomalies are gradually being replaced with the new period 1981-2010.
- The change in averaging period will alter the anomaly value reported for the particular month, season or year. For example, the UK mean temperature for July 2012 was 14.1 °C. This is 0.8 °C below the 1971-2000 July long-term average, but 1.0 °C below the July 1981-2010 long-term average.
- The UK annual mean temperature has increased by around 0.25 °C when comparing 1981-2010 with 1971-2000. This is a similar difference to that between 1971-2000 and 1961-1990.
- This trend in warming across the UK is consistent with that observed globally over land.
- While temperature has generally increased, there are differences depending on whether maximum, mean, or minimum temperature is considered, the region of the UK, and whether it is the monthly, seasonal, or annual value of interest. For example, the December mean temperature for the UK has actually decreased when comparing 1981-2010 with 1971-2000. This will partly be because of the influence of the exceptionally cold month of December 2010.
- Elements correlated with temperature in general show consistent trends. For example, the UK annual average number of days of air frost, and days of snow lying have decreased when comparing 1981-2010 with 1971-2000.
- The UK annual average rainfall has increased by a relatively small amount - around 2% - when comparing 1981-2010 with 1971-2000. This is a similar increase to that from 1961-1990 to 1971-2000.
- While most changes in average rainfall are small - typically less than 5% - it depends on the area of interest and whether monthly, seasonal or annual averages are considered. For example, the UK July average has increased by more than 10% when comparing 1981-2010 with 1971-2000. This will be influenced by a run of notably wet Julys from 2007 to 2010, whereas relatively dry Julys in the 1970s are omitted. In contrast, the UK monthly average rainfall for both September and December has decreased slightly.
- The increase in overall UK annual average rainfall may be partly explained by the fact that a warmer atmosphere will hold more moisture.
- The UK annual average sunshine duration shows a small increase when comparing 1981-2010 with 1971-2000. The averages for summer and autumn are almost unchanged, whereas those for winter and spring show modest increases (typically 5%).