Forecasters have said temperatures could reach a sweltering 33C in Suffolk this Friday after a heat-health alert was issued.
A warm flow of weather is set to arrive from Spain and Portugal, where daytime temperatures have exceeded 40C in southern Spain.
The UK Health Security Agency has said the Level 3 alert, which was initially at Level 2, will be in place from midnight on Thursday until midnight on Saturday.
During this time, people will be urged to check on those who are most vulnerable and look out for signs of heart and lung conditions.
People have already been making the most of the warm temperatures this week, with Southwold beach full of visitors on Wednesday.
Zoe Johnson, meteorologist at East Anglian forecaster Weatherquest, said: "It will be a warm day on Friday and the south-east will be where it is concentrated.
"The maximum temperature for our region could be 33C, possibly 34C at a push – though that may be in London. It will be a hot and humid day with plenty of sunny spells.
"For East Anglia, the average temperature for this time of year is around 20C, so we are looking well above the average."
Met Office spokesman Grahame Madge said: "Because of the direction of the flow, with the weather pattern we have got set up in our latitude, that is encouraging this warm flow of air to come further north.
"We have got the heat building day by day. The next couple of days will be hotter than the preceding day. We think at the moment, although there is some uncertainty, that the weather temperatures will peak on Friday and then largely we will be in for a cooler day on Saturday."
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