Temperatures in London are forecast to hit as high as 35C amid a fresh heatwave as an amber warning for extreme heat is issued.
The Met Office warning is in place on Monday and Tuesday for the capital as the mercury is expected to reach 31C and 35C respectively. Forecasters are predicting seven days or more of sweltering heat of at least 30C.
The temperature is due to hit 27C in London on Saturday before climbing to 30C on Sunday. Wednesday is also forecast to see temperatures of 35C, with 32C on Thursday and Friday.
A heatwave is officially defined by the Met Office as a period of at least three days when the temperature stays above a certain threshold. In London, this threshold is 28C.
The heat warning flags potential health impacts for people vulnerable to extreme heat and heat-related issues for the wider population, as well as a potential increase in water safety incidents.
The warning, which differs from amber heat health alerts issued by the UK Health Security Agency (UKHSA), comes as the heatwave is expected to sweep parts of the UK during the weekend and early next week.
Some locations may see temperatures remain above 20C overnight on Monday and Tuesday, particularly in urban areas.
Amber heat health alerts are in force by the UKHSA for the east, south-east and south-west of England, as well as London, until 8pm on Tuesday.
Greg Wolverson, deputy chief forecaster at the Met Office, said: “While heatwave criteria will be met for some in the south and south-east of England over the weekend, with temperatures into the low 30s possible, the warmth will expand and intensify at the start of next week, which, coupled with high temperatures overnight, leads to potential impacts.
“Temperatures will peak around the mid-30s on Monday and Tuesday. The humidity will also mean this feels close, warmer and more uncomfortable for many.
“Tropical nights – where the temperature doesn’t drop below 20C – are also likely for some.”
The warmth may bring some thundery downpours for some on Monday and Tuesday, though these should be “fairly isolated”, the Met Office said.
The very high temperatures could continue across a smaller part of the country into the middle of the week, but this remains uncertain for now, the forecaster added.
At least 15 people died after getting into trouble in open water during a hot spell in May.
Samantha Hughes, national water safety partner at the Royal National Lifeboat Institution, said: “With warmer weather approaching, it’s important to remember that the water is still cold.
“Entering it unexpectedly can lead to cold water shock, causing a sudden increase in breathing and heart rate, which may trigger panic.”
After the heat health alerts were issued, the Health and Safety Executive (HSE) said employers must ensure their workers are protected while maintaining productivity during the heatwave.
