Fresh thunderstorm warnings have been issued as temperatures look set to soar as high as 30C this weekend.
Parts of the country are predicted to be hotter than Marbella, Ibiza and Tenerife in the coming days as a “plume of warm air” moves in from the south, triggering thundery showers.
Forecasters have warned of the potential for sudden flooding on roads and of homes and businesses.
Met Office spokesperson Stephen Dixon said: “What we see later in the forecast and today is the start of a bit of a change in tide through the weekend, which will see temperatures increase, but also increase the chances of some impactful, thundery showers for some.
“As we move into Sunday, that risk really persists in terms of thundery downpours being possible.
“A second yellow thunderstorm warning has been issued from midday on Sunday through to 9pm on Sunday.”
The UK Health Security Agency (UKHSA) has issued an amber alert for hot weather in the West Midlands, East Midlands, East of England, South East and South West.
It means the impact of the heat is “likely to be felt across the whole health service … and the wider population, not just the most vulnerable”.
There was a sharp rise in the number of extra deaths, or “excess deaths”, during the summer heatwaves of 2022, according to the Office for National Statistics.
Excess deaths are the number of deaths above the long-term average for that date of the year.
Some 638 excess deaths were recorded as taking place in England and Wales on July 19, when temperatures in the UK topped 40C for the first time – the equivalent of 48% above the long-term average.
A further 496 excess deaths took place on July 20, or 37% above average.
During the four days from August 12 to 15, when temperatures climbed to the mid-30s, 1,120 excess deaths took place, including 348 on August 15, the equivalent of 28% higher than average.
A further yellow alert, which is less serious and warns that there may be some disruption to services due to weather conditions, is in place for the North East, North West and Yorkshire and Humber regions of England, as well as London.
All alerts are in place until 9am on Monday.
The Met Office said thundery showers may continue into Monday particularly in southern and central England as well as in Wales.