A mini-heatwave in Britain this week could feel as hot as 111F (44 C) as soaring temperatures arrive accompanied by sticky humid air, forecasters have warned.
All-time records for July could be broken on Wednesday or Thursday as the mercury pushes towards 95F (35C) and above.
Public Health England (PHE) has issued a level-2 ‘alert and readiness’ warning with older people urged to close their curtains and avoid going outside during the hottest part of the day.
Netweather charts show high humidity could make temperatures 'feel like' 111F (44C) before the end of the week as sweltering humidity pushes north from the Continent which is braced for a potentially killer heatwave, with Paris expected to hit 105F (41C) by midweek.
Malcolm Booth, chief executive of the National Federation of Occupational Pensioners (NFOP), said the elderly and vulnerable should take extra care because summer heat can be as deadly as winter cold.
“With very high humidity this can affect elderly people and those with breathing problems more severely,” he said.
“People should prepare for this in order to prevent a spike in excess summer deaths due to the heat.
“Stay indoors during the hottest periods and if you live close to people who might be struggling in the hot weather take a minute to check if they are alright.
“Keeping curtains closed to keep the sunlight out during the hottest part of the day can also help keep temperatures down.”
Thursday could see temperatures beat the all time high for July 25 of 93F (33.9C) which was recorded at Regent’s Park London, in 1900.
And the 98F (36.7C) record for the month could be under threat over the coming days if the heat holds out until the weekend, the Met Office said.
Even the north could see temperatures of 86F (30C) although ‘explosive’ thunderstorms later in the week could bring much cooler conditions, torrential rain and some flooding,
Meteorologist Sophie Yeomans, from The Met Office, said: “The hot weather is coming up originally from Africa and through France and Spain which are going to see heatwave conditions again this week.
“By Wednesday we expect temperatures in the UK to reach 93F (34C) during the second half of the week it is uncertain whether there will be a trend back to fresher conditions.
“If the heat remains temperatures could rise slightly higher.
“During the first part of the week while high pressure builds over southern Britain, it will be a slightly different picture across the northwest which is still stuck in the jet stream. Low pressure will come into the north and there will be a fair amount of rain.”
Hot air is moving up from north Africa and the Mediterranean into Spain - where conditions could reach 109F (43C) by Tuesday.
But thunderstorms could be seen on Wednesday and Thursday in the west of Britain before shifting further east.
Ex-BBC and Met Office forecaster John Hammond of the website Weathertrending.com said: “A brief blast of heat may see the hottest weather of the year so far.
“But the thundery breakdown following looks potentially explosive.”