June 2023: UK was Hottest in the West

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Shortly after I hit “publish” yesterday, the Met Office did the same. Their analysis of the UK temperatures this June showed that the average UK temperature of 15.8C far exceeded the previous record in their data series of 14.9C in 1940 and in 1976, no doubt demonstrating the effects of climate change, a point made across the broadcast media.

I agree, of course, that such an exceptional June mean temperature does have the fingerprints of global warming all over it, particularly as this June’s weather didn’t seem that exceptional. In 1976, I notice, daily records were broken every day from 23rd-28th June, exceeding 35C on the last 3 of those days.

I pointed out yesterday that the Met Office data for UK-wide temperatures goes back only to 1884, and in the long-running Central England Temperature (CET) record, there have been hotter Junes than in 2023, notably at the start of the long, hot summers of 1846 and 1826. The Met Office failed to address this, or even mention the CET record, so one might argue that the heat of June 2023 is a rare event that simply hasn’t occurred during the period of their dataset.

There is evidence, though, in the Met Office press release that the heat of June 2023 is due to global warming. What struck me was the distribution of the high temperatures:

Fig 1: June 2023 UK temperature anomaly map, from Met Office press release

Clearly, the most extreme temperatures were experienced in the west of the UK.

So, whilst the UK mean temperature far exceeded that in previous years:

that for England alone was less exceptional:

Fig 3: England mean temperatures from Met Office website

And if we consider that the CET series represents an area mostly in the pink rather than red part of Fig 1, it’s no surprise that it was even less exceptional:

Fig 4: CET mean temperatures for June, my graph using Met Office data

Fig 4 is an updated version of the figure included in yesterday’s post, using the latest data (which I mentioned a while back). This included an adjustment downwards for June 1976, which now shows as slightly less hot (at 16.9C) that this June (17C).

Perhaps, one might suppose, there has been some extra warming this June in the west of the UK, giving disproportionately higher temperatures there, explaining why the June 2023 CET mean temperature is less exceptional that the June 2023 UK wide (or Scottish and Welsh) mean temperatures. Could this be the case?

Well, yes it could. Sea surface temperatures around the UK have been exceptional this year:

Fig 5: Sea surface temperatures, from the Guardian

Warmer than usual air off the Atlantic may explain the more exceptional 2023 temperatures in western areas of the UK as shown in Fig 1. Assuming this western warming effect didn’t also happen – without global warming – in the historically record hottest Junes in the CET, such as 1846, it’s possible that, if we had UK-wide and not just CET data back to the 17th century, June 2023 would be at least close to the hottest of all time and not just the hottest since 1884.