An amber heat health warning has been issued for London as temperatures are forecast to soar above 30C in the second heatwave this year.
They are set to reach 34C in the capital, and 35C at Heathrow airport on Tuesday.
The UK Health Security Agency (UKHSA) issued alerts for parts of England until Tuesday evening.
This includes the East of England, South East, South West and London.
Forecasters are predicting seven days or more of sweltering heat of at least 30C.
The temperature is due to hit 29C on Friday in London, rising to 32C on Monday, peaking at 34C on Tuesday, falling to 30C on Sunday before cooling further, according to BBC Weather.
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.
Londoners should brace for two tropical nights as temperatures on Monday night will not drop below 22C.
Tuesday night looks to be even warmer, with temperatures of 28C forecast in London as late as 10pm.
A tropical night is the name given to a night when the temperature does not drop below 20C. The capital saw its first tropical night of the year last month in May’s record-breaking heatwave, which saw the UK’s hottest-ever May day.
Dr Agostinho Sousa, Head of Extreme Events and Health Protection at UKHSA, said: “Sustained periods of warm weather can result in serious health outcomes, especially for older adults, and it is therefore important that everyone takes sensible precautions while enjoying the sun.
“We are urging health and social care services in affected regions to ensure they are prepared, and reminding people to look out for elderly relatives, neighbours, and those with underlying health conditions, making sure they are aware of the forecast and following the necessary advice.
“Simple steps such as staying hydrated, avoiding the sun during the hottest part of the day, and keeping your home cool are some of the key ways to help keep yourself and others safe during periods of hot weather.”
Met Office Deputy Chief Forecaster Gregory Wolverson said: “This week’s weather reflects a contrast we often see in summer, with more unsettled conditions passing to the northwest of the UK while heat builds in the south and east. As we move towards the weekend, we’ll see conditions become more widely settled and temperatures rise all round. Many parts of southern and eastern England are likely to see temperatures high enough to meet heatwave thresholds.”
The heat is building across Europe this week due to persistent high pressure🌡️
— Met Office (@metoffice) June 17, 2026
Maximum temperatures could reach around 40°C in parts of Spain, France and Italy over the weekend
Minimum temperatures will not fall much below 20°C, leading to some tropical nights pic.twitter.com/vr5TnhqeaE
Last week, the mayor’s office warned that middle-aged Londoners are at the same risk of dying in a heatwave as pensioners.
Sir Sadiq Khan’s officials highlighted these factors to an inquiry by the London Assembly’s Planning and Regeneration Committee called: London is overheating - are our homes ready for rising temperatures?
“Most heat-related excess deaths in England are in those aged 65+ years,” the London Mayor’s Office said in written evidence to the committee amid forecasts of another period of warm weather in coming days.
“Whilst heat risk is strongly correlated with older age, there is evidence that younger adults in London have a disproportionate level of risk, with Londoners aged 45-65 years having the same risk of dying during hot weather as those aged 65+ years.”
The Greater London Authority has released a map to help people combat the unprecedented weather over the summer months.
