Guernsey's heatwave ends with a thunderstorm after hottest day ever

Friday, 26 June 2026 07:55

By Euan Mahy

Thunder rolled in from France after Guernsey sizzled in its hottest ever recorded temperature.

The heat yesterday (25 June) was deceiving, as the day began slightly fresher than the previous few.

But by lunchtime the heat had built steadily and in the early afternoon Guernsey Airport recorded 36.4°C - the hottest ever summer temperature - beating the 2003 record of 34.3°C by 2.1C.

The temperature in Jersey was close to 40°C - 39.3°C was recorded at Maison St Louis in St Helier- and this easily broke the island's all time record of 37.9°C,

During the late afternoon the forecast thunderstorms from Brittany began to be visible as a darkening mass of cloud out to the west.

This missed Guernsey but at 9pm a front further east brought thunder and a brief downpour which added to the feel of a what is classed as a tropical night, where the temperature is 20°C or more.

The heatwave has been described by Jersey Met as 'exceptional and historic' and it is not over for the southern UK, where the red extreme heat warning continues.

Annie Masterman, the duty forecaster at Jersey Met, says temperature extremes will keep happening.

"What we're seeing with these kind of historic temperature records being broken is these warm heatwaves moving across the islands, and that's symptomatic of this overall pattern we would expect to see with climate change."

As the heat built over five days, many islanders swam, lingered over their shopping in air conditioned supermarkets and sought out fans and air coolers to battle it.

The head of retail at Guernsey Electricity, Malcom Woodhams, describes the demand as 'unprecedented.'

"The website is seeing sales going through the evening and right through the night as well.

"People are having an uncomfortable night's sleep and are looking to see if there’s anything available; we've seen loads of sales coming through."

Across the Bailiwick it is fresher and the forecast high of 24°C is 12°C lower than yesterday's peak.

The last week of June and into July is forecast to see a mix of sun, cloud and the odd shower, with temperatures in the low 20s.

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