So, was this heatwave "the one"? No I don't think so. Not yet.
I'd been thinking over the last 3 or 4 years that sooner or later we would have a heatwave in the UK that is extreme both in severity and duration. Not just because of some statistical supposition based on climate change and the shifting of the bell curve, but because the models have shown a number of such events, at least once or twice per summer and across multiple runs not just one freakish ensemble perturbation.
Compared with some runs even earlier this summer, this heatwave while certainly unusually hot fell quite a long way short. I think that is reflected in the fact that we still didn't get to anything like the duration or countrywide nature of the heat of July 1976 or for that matter August 2003 (let alone the month long heat of 1976, 2006, 1995, 1997).
2018 was not the one either. It was persistently very dry and sunny, and pretty warm/hot, but without any real sustained period of major heatwave. There were some runs in late July 2018 which if they'd come to fruition would have sent that summer squarely into the record books with a very hot August, but they never came to pass. Instead it got cooler and wetter.
Areas where August 2020 fell short in terms of synoptics / airmass:
- Pressure was never that high meaning there was always a lot of cloud around
- the source airmass, while hot, was nowhere near as hot as in say June or July last year. France's canicule this year was decent but nothing special. We spent several days in 850s of upper teens, which is enough for very hot weather, but I have seen many runs taking us to 21 or 22C and staying there for a few days
- on most days the hot air never made it that far into the UK. Contrast with 2018 when the hottest place was Porthmadog 3 days in a row. This was largely an event of the far South East
- it wasn't combined with a long standing drought
Either those runs that occasionally turn up on the models are just makebelieve, or "the one" will happen at some point in the next decade. This feels like it was a warm up.
Still, it is great finally to get some proper hot weather in August. It's been so long, August has become a real anomaly among months.