Parts of Britain could sizzle in staggering 37C heat on Friday on what is likely to be the hottest July day on record.
The mercury could top the previous July record of 36.7C recorded at Heathrow Airport on July 1 2015 by the end of the week, the Met Office said.
Despite soaring temperatures forecast in London and the south-east, yellow weather alerts have been issued over fears of torrential downpours in the north by the weekend.
An amber "heat health watch" warning also remains in place for parts of England, with people being urged to try to stay out of the sun between 11am and 3pm.
Nurses have warned that some hospital wards have reached more than 30C, leading to patients and relatives passing out or vomiting
But as temperatures continue to soar, parts of the country could face thundery downpours over the weekend forecasters warned.
There is also a chance East Anglia will see some thunderstorms as early as Wednesday.
The break in weather comes after the heatwave baking Britain saw parks and beaches packed with sunbathers
Motorists have been warned that roads could melt in the blistering heat while medics raised concerns about temperatures on hospital wards.
The Society of Acute Medicine flagged up fears about the safety of patients and staff in overheated hospitals.
Dr Nick Scriven, the society's president, said while most hospitals are designed to keep patients warm all year round, they can become too hot in such high temperatures.
The Royal College of Nursing raised concerns that some nurses are unable to keep properly hydrated during their shifts as they are not allowed to take water bottles on to wards.
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The Local Government Association said social workers, community wardens and maintenance staff are all on high alert to identify those who could be struggling in the heat.
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And pet owners have been urged to avoid exercising their dogs and other animals in the hottest parts of the day due to the risk of burnt paws on scorching pavements.
