Over the last couple of days I’ve posted charts of temperature (1884-2020) and rainfall (1862-2020) for the UK from the freely available gridded data series from the Met Office. So I thought I would complete the series by taking a closer look at sunshine since 1929 by means of a 12 month moving average and a linear trend to see if the UK has become any sunnier in that time. It’s a shame that the Met Office haven’t extended the sunshine series back any earlier than 1929. Obviously data will be quite thin on the ground, but the Campbell-Stokes sunshine recorder has been around since 1853, and daily sunshine totals from a dozen or so climate stations has featured in the DWR since the start of the 20th century. Anyway, the chart below shows the 12 month running sunshine totals since 1929 with numerous peaks and troughs in sunshine that have occurred during that time. Perhaps I should overlay the sunspot cycle to see if there is any correlation between the two! The only thing I can spot with any certainty at this range is the peak of sunny summers around 1975 and 1976. The linear trend does show that the UK has been very gradually getting sunnier in the last 90 years, with an extra 12 hours of sunshine annually each decade.
Looking at just the last 30 years the rate of increase in annual sunshine per decade has more than doubled in that time (26.7 hrs/decade). I will do some further research to see exactly which month of the year is contributing most to that increase, and report back. It looks like the highest rolling total of sunshine since 1929 occurred in the spring of 2019 (because this a trailing average that would have been for the period between spring 2018 and 2019), and likely the result of the sunny summer of 2018.