CryoraptorA303 The most noticeable thing of all is that in the Heathrow record, there have been 12 Septembers sunnier than the preceeding August. No big deal, until you look at the years in question.
1958, 1968, 1971, 1979, 2006, 2008, 2010, 2011, 2015, 2018, 2020, 2021.
What did happen once a decade on average is now happening almost half of the time since 2006.