A forecaster said: “A fine start will lead into a very hot day, with lengthy sunny periods and a humid feel given the light winds.
“While remaining hot, more clouds may develop later, with a small chance of isolated severe thunderstorms. Maximum temperature 34C.”
The UK Health Security Agency has issued a yellow heat health warning for much of the UK through to 9am on Wednesday.
Among the safety warnings being given to Londoners is a caution against swimming in unpredictable waters.
Met Office forecaster Craig Snell said: “It’s going to be hot. The weather is coming with a lot of humidity, so it will feel quite uncomfortable out there across central eastern England.”
Indeed, other parts of the country are being battered by storms and more than 5,000 lightning strikes have been recorded in the past 24 hours.
Northern England, Scotland and Northern Ireland are worst affected.
Here are the areas that the Met Office has flagged to be at risk.
Yachts sail through the water at Bristol Harbour
Ben Birchall/PA Wire
Areas covered by the yellow heat health alerts
According to the Met Office, yellow alerts may be issued during periods of heat, which would be unlikely to affect most people apart from those who are particularly vulnerable.
The yellow alert extends to.
Areas covered by green heat health alert
A green alert has been issued for the North-East, which the Met Office said means: “No alert will be issued as the conditions are likely to have minimal impact on health.
“However, during periods where the risk is minimal it is important that organisations ensure that they have plans in place and are prepared to respond should an alert (yellow, amber or red) be issued.”
