LONDON - The Met Office warned healthcare providers to be ready to help high-risk groups on Wednesday as Britain's heatwave looks set to intensify.
Temperatures were expected to reach 32C (89.6F) in London and 31 in the southeast on Wednesday, while other areas of the country could see daytime temperatures of 28 to 30C.
Forecasters say the hot and humid conditions -- Britain's first prolonged heatwave for seven years -- could continue for the rest of the month and into the early part of August.
"There is a 90 per cent probability of heatwave conditions between 0900 on Wednesday and 2100 on Thursday in parts of England," the Met Office said on its website.
It raised its three-stage hot weather warning for those looking after potentially vulnerable groups like children and the elderly to "be prepared" from "be aware."
The Department of Health issued its own advice on how to cope with the heat.
"Keeping the home as cool as possible during hot weather and remembering the needs of friends, relatives and neighbours who could be at risk is essential," it said.
"The elderly and those who are ill are particularly vulnerable during hot weather, and the most oppressive conditions occur in our towns and cities."
Heat can make heart and respiratory problems worse, and in extreme cases can lead to potentially fatal heat stroke, it added.
Despite the dangers, the heatwave makes a pleasant contrast for many Britons after last year's washout Summer and the coldest Spring this year for more than 50 years.
Britain's hottest July temperature was 36.5C, recorded in Surrey in 2006. The hottest ever in the UK was 38.5 (101.3F) degrees recorded in Kent in 2003.