Four seasons getting wetter

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If you examine the England and Wales series of daily precipitation which started in 1931, you’ll hopefully find as I have, that each of the four ‘meteorological’ seasons have been getting progressively wetter. Winters are now almost 20% wetter than they were in 1931, that equates to 78 mm of extra rainfall. Summers on the other hand show the lowest rate of increase, just 4.2%. In fact if you look examine the linear trend of rainfall during the ‘calendar’ summer, the 21st of June to the 20th of September, you’ll see that it’s 2.7% drier than it was back in 1931, not a lot of people know that.

  • Winter +19.9%
  • Spring +9.3%
  • Summer +4.2%
  • Autumn +6.7%
  • Annual +8.8%

Annually using this series England and Wales are 8.8% wetter in 2019 than they were in 1931. Curiously if you examine the newly extended gridded data back to 1862 using a simple linear trend, annual rainfall totals have changed very little in the last 157 years (+1.4 mm). All that I can assume is that the period between 1862 and 1931, was as wet, or even wetter than it is now.

The daily UKP data is free to download from the Met Office, and hopefully in the near future, that too will be extended back to 1862 as the rest of the monthly gridded data recently has, this might help give greater clarity into the underlying natural climatic variability of rainfall across the UK and how it’s changed.

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