Jersey Met predict it will hit 35°C in Guernsey today (23 June), after the June heat record was broken yesterday.
Guernsey's current record hottest day of 34.3C was achieved in early August 2003, but today the temperature is expected to rise to 35°C.
It reached 32.2°C yesterday, (22 June), which beat the June hottest temperature record of 30.8°C.
The Channel Islands are being affected by a 'heat dome' covering western Europe, where some places are exceeding 40 Celsius.
The possibility of reaching that temperature has not been ruled out for Jersey this week.
The extreme conditions are expected to continue until Thursday night, with temperatures in Guernsey remaining at 34 or 35°C on Wednesday and Thursday.
Guernsey Water will feel the brunt of the heatwave and expects daily demand to increase by 1.5 million litres or more, which was the peak heatwave figure in May this year.
Operations manager Jon Holt says common sense measures, like not wasting any tap water and reusing kitchen water in the garden can cut demand:
"Simple, sensible actions taken by thousands of customers can overall make a real difference, ensuring that the reduction in storage levels is as low as possible.”
Those with a physical health issue can find extremes of heat challenging, and the advice from the healthcare sector is to stay inside if possible between late morning and early evening, shut curtains facing the sun and keep hydrated with water.
Nurse advisor Emma Baker says heat exhaustion can be a problem:
"Move yourself or the individual into a cool place, remove any unnecessary clothing like socks or jackets, drink plenty of cold water or perhaps have a re-hydration drink, and cool the skin down with a sponge."
Animals are equally as vulnerable to the heat and the advice from the GSPCA is keep them out of the sun and do not walk dogs on tarmac which can reach temperatures that burn their paws.
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