Jersey set for another heatwave

Jersey could be set for another heatwave, and what could be the longest hot spell so far this year.

A heatwave is officially at least three consecutive days above 28°C.

We're forecast highs of 29°C on Friday (15 August), and then a run of very warm conditions across the weekend into next week.

Tuesday (19 August) is currently expected to be the end of this very hot spell, with a predicted 29°C before falling back to the mid-twenties on Wednesday.

The average temperature for this time of year in Jersey is 22°C.

The hottest day of 2025 so far came on 30 June when it reached  33.4°C in St Helier.

Read: Hottest June day on record

We have already had three official heatwaves in Jersey so far this summer, that is three separate periods where the maximum daily temperature recorded as exceeded 28°C for three consecutive days or more.

Dave Rigby, senior forecaster at Jersey Met, warns that it will be hotter than it feels.

"It you want relief, then I have good news for you.  The weekend looks quite breezy - a brisk force 4 or 5 - so that will make it feel closer to 24°C rather than 28°C. 

"But with the wind, if you don't feel as hot you won't notice the sunburn, but you will get just as sunburnt with the wind."

Public Health advises to stay hydrated, seek out the shade, and wear a hat and sunscreen to avoid the risk of sunstroke and heat exhaustion.

• avoid going outside during the heat of the day (midday to 6pm) 
• leave strenuous activities for the evening when it is cooler 
• take cold baths and showers 
• drink plenty of water and avoid coffee and alcohol 
• keep your home cool by closing curtains, opening windows and using fans 
• wear a hat and loose light clothing, try to stay in the shade and carry water with you

Director of Public Health, Professor Peter Bradley, said: “While the warm weather is enjoyed be most, extreme heat can cause harm to health including heat exhaustion, heatstroke, and dehydration, particularly the most vulnerable in the community. I encourage all Islanders to take precautions and stay safe in the hot weather.”

The sea is warmer than usual for the time of year too.

The highest temperature recorded so far in 2024 was 19.4ºC earlier in August.

That measurement is taken from a sensor in St Helier harbour.  

The last time a temperature above 20ºC was recorded here was on 9 August 2003, at 20.4ºC

Jersey Met has written a blog about the higher-than-average sea surface temperatures.