Britain could be in the midst of the longest spell of hot June weather for more than 20 years as the country is gripped by a heatwave.
Highs of 34C (93F) are forecast in west London on Wednesday, which would make it the fifth consecutive day that temperatures have topped 30C (86F) in the UK, the Met Office said.
The last time the country saw a similar run of hot June weather was in 1995.
The Met Office has issued the second highest heatwave alert for England as temperatures continue to soar.
The level three amber warning - one behind a national emergency - has been issued until 9am on Thursday.
Met Office spokesman Grahame Madge said: "It is likely that we'll have five days in a row with a weather station somewhere in the UK recording 30C or more - from Saturday until tomorrow.
"The last time that we had five days in a row in June above 30C was from June 26 to June 30 1995."
Monday saw the UK's hottest day of the year, with 32.5C (91F) recorded at Hampton Water Works in Greater London.
A teenage boy drowned in a reservoir at Greenbooth Reservoir, a moorland beauty spot outside Rochdale, Greater Manchester, after reportedly getting into difficulties while swimming in the hot weather.
A woman in her 80s also died after being pulled from the sea at East Wittering beach in West Sussex on Monday afternoon, Sussex Police said.
In Guildford, Surrey Police said spilt oil had melted into a tarmac road due to the scorching conditions.
Temperatures could climb to 33C (91F) on Tuesday and possibly hit a sweltering 34C (93F) on Wednesday in west London.
At Royal Ascot in Berkshire, where temperatures could soar to 28C (82F) on Tuesday, race organisers were considering relaxing the strict dress code for the first time.
An Ascot spokeswoman said: "It's being considered. We're waiting for confirmation. It's never happened before."
Music fans arriving at Glastonbury festival on Wednesday will face a sweaty walk to pitch their tents with highs of 30C (86F) expected.
The NHS has urged the elderly, children and those with medical conditions to keep cool and hydrated during the heatwave.
Those at risk are warned to keep in the shade during the hottest part of the day between 11am and 3pm.
But Mr Madge said thundery rain will move across England on Thursday, bringing the hot weather to an end.
He said: "Quite a heavy belt of thundery showers will be moving eastwards and that behind it will pull in slightly cooler fresher air.
"There's a chance that the South East will hang on to the heat for longest."