Saturday 30th May
Although the maximum temperature on Friday was down again, with a peak of 24.6C at 16.55, the UV level with a value of 6.3 was at the top end of the high category making it the strongest this month. Under clear skies the warmth steadily dissipated giving us the coolest night since the 18th with a low of 8.0C at 05.24. The high was 7.3C above average whilst the low was 1.0C above average.
Saturday arrived with sunshine from the start, after sunrise in Marlborough at 04.58, that resulted in the temperature recovering to 15.7C by 08.00.
The modest ridge of high pressure will today give is the last of the very sunny and very warm days and is fending off a cold weather front during daylight hours that will pass our area in the early hours bringing a significant change to more cloud and cooler temperatures by day, from Sunday onwards.
During the past week the jet stream has been arching above the UK putting us on the warmer south side allowing the high pressure to dominate from the Azores whilst from tomorrow the jet stream, rushing across the Atlantic, will push weather fronts across the country bringing much cloud, temperatures near average and the strong possibility of showers on most days.
The significant feature of the heatwave was the speed at which the heat built up, referred to as a ‘heat spike’.
Are ‘heat spikes’ becoming more common?
Simon King
Lead Weather Presenter
With temperatures hitting a record breaking 35.1C this week, it has been an exceptional May heatwave.
In its build up we saw temperatures increase rapidly – by up to 10C in just two days in some locations.
Historically, it would have been more common to see a gradual increase of a degree or two each day.
The rapid onset from an average to high, even extreme, temperature – or a “heat spike” – is something I and fellow meteorologists have noticed happening more often.
Ed Hawkins, professor of climate science at the University of Reading, told the BBC that “Today’s heat events are emerging earlier, intensifying faster and occurring across a much warmer background climate”.
While according to Dr Ségolène Berthou from the Met Office, “We can’t explicitly say that extreme heat temperatures spike faster now than they did in the past,” experts are beginning to piece together a number of other factors that could provide an explanation.
Hotter days give a ‘head start’
The Met Office’s State of the Climate 2024 report shows that in parts of the UK the hottest days are warming around twice as fast as typical days. Compared with 1961-1990, the number of days 5C above average has doubled, while days 10C above average have quadrupled
Or as Dr Berthou expresses it: “Extreme temperatures are increasing faster than average temperatures.”
Summer daytime highs are already about 1.5C warmer when comparing the 1991-2020 climate period with 1961-1990.
After the UK hit 40.3C in July 2022, Met Office studies showed the likelihood of exceeding 40C is now more than 20 times higher than in the 1960s.