Health chiefs have upgraded a yellow alert for the weekend to an amber heat-health alert in five regions as the Met Office said temperatures could hit a scorching 30C this weekend.
The amber alert, which covers southeast England, the West Midlands, East Midlands, east of England and the southwest, means there is a greater risk to everyone’s health – and not just the vulnerable.
“There is a high likelihood that forecasted temperatures will be reached rapidly over the weekend in these regions, while we are also likely to see high overnight temperatures,” the UK Health Security Agency said.
A “plume of warm air” from the south is expected to push the mercury up, the Met Office said, with a chance of 30C for some parts of England this Saturday.
Those areas could be hotter than Ibiza and Milan, where temperatures will reach 28C.
An amber alert indicates the effects are likely to be felt across the whole health service, and the wider population could suffer, not just the most vulnerable.
A yellow alert has also been issued for the northeast, northwest and Yorkshire and Humber regions of England. London remains at this level.
Both alerts cover 9am on Friday to 9am on Monday.
The alerts have been issued under a new colour-coded warning system for heatwaves, launched by the agency and the Met Office.
Thursday was the warmest day of the year as temperatures in Hurn reach 25.4C, above the previous high set in Porthmadog last week.
The “big changes” in the weather will begin from Friday, according to Met Office meteorologist Aidan McGivern, as “high pressure that has brought easterly winds for three weeks or more moves a little to the east allowing low pressure to approach from the southwest”.
There has been little to no rain in the UK in last three weeks, new figures showed. Less than one millimetre rain has fallen in the southeast and northeast since 31 May, with the rest of England seeing no rain at all.
These changes will be “increasing the humidity” and “leading to higher temperatures and an increased chance of showers and thunderstorms”.
Saturday morning clouds will slowly start clearing, giving way to plenty of sunny spells, the Met Office forecast said.
As the day progresses, it will turn increasingly hot and humid. The high temperatures are expected to trigger showers, some of which could be “torrential and thundery”, with more than 30-40mm potentially falling within an hour.
Rain, hail, wind and lightning are also predicted to hit some areas, although others parts of the country will see no rain at all.
Some localised flooding is possible, the forecaster said.
A thunderstorm warning is running from 2pm to 9pm on Saturday, in cities including Manchester, Cardiff and London.
Oliver Clayden, from the Met Office, said there could be some travel disruption over the weekend.
“After a prolonged dry spell there is a chance of surface water flooding,” he said.
“There could be some surface water issues that could cause travel disruptions as well as the high gusts across parts of the country.”
“This is going to be the warmest weekend of the year, which is to be expected as we go into summer,” Mr Clayden said.
“This weekend will also see hail mixed in with strong gusts of wind and rain hit parts of the country.”
