A series of health alerts have been issued as forecasters warn parts of the UK will turn "very warm and humid" with temperatures potentially reaching 30C.
The UK Health Security Agency (UKHSA) said the yellow heat health alerts would apply to the East of England, East Midlands, London and the South East from 3pm on Wednesday until 8pm on Monday.
The conditions are likely to cause a greater risk to life for vulnerable people along with an increased use of healthcare services, officials said.
The UKHSA also said water-related risks may rise, including those associated with drowning and cold-water shock.
Forecasters said southern parts could see temperatures reach 30C on Friday - but it could also turn "rather lively" with thunderstorms, while heavy rain may sweep into other areas.
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Sky meteorologist Steff Gaulter said: "The UK is sandwiched between an area of low pressure in the Atlantic and an area of high pressure that's in charge across Europe.
"For northern and western parts of the UK, it'll be the low pressure that dominates this week and we can expect things to be rather unsettled with some heavy rain at times.
"But in the South East, the high pressure will extend over us, and warm weather will seep in from the continent.
"This is where the temperatures will build and where we could see temperatures touching 30C later on Friday.
"There's the chance that the hot weather could spark off the odd thunderstorm, so it might turn rather lively."
Read more:
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The Met Office said high pressure was starting to build and there is a "warm plume moving up through continental Europe" - with southeastern parts of the UK expected to turn "very warm and humid" from Wednesday.
In contrast, some northern parts can expect "further rain at times" on Thursday and Friday, the agency said.
(c) Sky News 2026: UK weather: Health alerts issued as temperatures could hit 30C
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