Thursday was provisionally the hottest day of the year so far, with 32.6C recorded in Wisley, Surrey, the Met Office has said.
The previous highest temperature for the year was set in June at 32.2C.
The heatwave has also broken the record for the most consecutive days with temperatures above 30C in September, according to the forecaster, with Saharan dust generating vivid sunsets and sunrises in the clear conditions.
Thursday was the fourth day above 30C, beating the record of three days seen on four previous occasions, most recently in 2016.
The high temperatures are expected to continue through the weekend, peaking as high as 33C on Saturday.
September’s highest daily temperature reading was 35.6C recorded on September 2 1906 in South Yorkshire, according to the Met Office.
Meteorologist Simon Partridge told the PA news agency there was “no chance” that the September daily temperature record could be broken in the coming days.
He said: “There is potential that we might get a little bit warmer over the weekend, not by a massive amount, but enough to make it the warmest day of the year so far again.
“It is always going to be around 32, close to 33 at the maximum temperature.”
The forecaster added there could be heavy thundery showers on Sunday across England and Wales but temperatures will remain high.
Prolonged heat above 30C leaves older people and those with respiratory or cardiovascular diseases at greater risk, with the UK Health Security Agency issuing an amber warning until 9pm on Sunday evening in nearly every area of England.
A yellow heat alert is in place until the same time in the north east of England.
The Met Office said in a post on X, formerly known as Twitter: “After getting very close yesterday, today is provisionally the hottest day of the year so far, with 32.6°C recorded in Wisley.”
Councils have also made preparations to stop roads from melting in the heat, the Local Government Association (LGA) said.
Councillor David Fothergill, chairman of the LGA’s community wellbeing board, said: “Extreme heat can also lead to changes to council services where necessary.
“This includes waste collections being undertaken earlier and additional support for those who receive adult social care.
“We also have found this year that around half of councils have made preparations to treat road surfaces with sand to prevent them from melting.”