Parts of the UK are on track to record a heatwave this week as temperatures soared above 30C (86F) on Tuesday.
Continuing sweltering conditions saw the mercury level rise to 31.3C (88.3F) at Frittenden in Kent, while 30C (86F) heat was felt at London's St James's Park, Cavendish in Suffolk and Writtle in Essex.
According to the Met Office, the last time it recorded a September temperature of 30C (86F) or more was back in 2016 when 34.4C (93.9F) was logged in Gravesend in Kent.
Since digital records began in 1961, there had only been six previous years where temperatures of 30C (86F) or more were recorded in September: 1961, 1973, 1999, 2006, 2013 and 2016.
A Met Office verified heatwave requires three consecutive days of temperatures above a certain threshold.
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In London this is 28C (82.4F), in counties near the capital such as Essex it is 27C (80.6C), while further away in areas such as Dorset and Somerset it is 26C (78.8F).
Met Office meteorologist Luke Miall said: "We've only had two days so far, so technically we are not in heatwave conditions yet.
"However tomorrow we are forecasting to see temperatures of 27C to 29C across parts of southern and south-east England tomorrow afternoon.
"So by tomorrow, we will then officially classify it as a heatwave for some areas."
Mr Miall said that with temperatures forecast to drop away by Thursday, the potential "localised heatwave" would only be a "three-day event".
He said it was more likely that parts of Kent, Surrey, Dorset and Devon could see a heatwave classified, but potentially not London.
Mr Miall said that "hot events" could become "slightly more frequent" due to the changing climate with further 30C (86F) conditions in September possible in the future.
This week's warm weather has been driven by winds around an area of high pressure centred over the east of the UK dragging in air from the continent, Mr Miall explained.
On Wednesday, conditions will be cooler in Scotland and eastern England, with some areas seeing a 10-degree drop in temperature.
Cooler and fresher conditions are predicted for Thursday and Friday, with temperatures in the south falling to low 20Cs in the south, and sunshine widely forecast.
Temperatures this week will still fall short of the highest September temperature ever recorded, which was 35.6C (96.08F) on September 2 1906.