The UK has recorded its highest temperature since the end of July as the country basks in some early autumn sun.
The mercury reached 30.7C at Gogerddan, in Dyfed, Wales, on Tuesday, the Met Office said.
It is the highest temperature since the 31.2 C recorded at the same location on July 22 this year.
Elsewhere, temperatures reached 30.4C at Northolt in west London, 30.3C at Pershore in Worcestershire and 30.2C at Heathrow, west London, and at Santon Downham in Suffolk.
The Met Office said that the recordings meant it was only the seventh time temperatures have exceeded 30C in September in the last 50 years.
Four of the previous instances came within the last 15 years – 2006, 2013, 2016, 2020 – with the other occasions in 1999 and 1973.
The warmest UK September day on record was on September 2 1906 when 35.6C was recorded at Bawtry, South Yorkshire.
The hot conditions have come after the official end of summer, from a meteorological point of view, which is considered to be August 31.
Tuesday’s temperatures mean that, with dry and fine conditions expected for some spots on Wednesday, official heatwave thresholds were likely to be reached in parts of eastern England this week.
A location meets the UK heatwave threshold when it records a period of at least three consecutive days of daily maximum temperature levels meeting or exceeding thresholds which vary across the country.
These include 25C for Wales, Scotland and south-west England, 27C for southern and eastern England and 28C for London.
Met Office meteorologist Marco Petagna said it appeared one location, Wiggonholt in West Sussex, had already met the heatwave thresholds, with recordings of 27.1C on Sunday, 28.6C on Monday and 28.5C on Tuesday.
Mr Petagna said the hot weather was “not that unusual” for the first half of September, but it would be “more unusual” for it to occur later in the month.
He said if a temperature of more than 28.1C was recorded in Scotland on Wednesday, it would be Scotland’s hottest September day since 1906.
There was a 30% to 40% chance of this happening, Mr Petagna said.
The Met Office earlier tweeted that a “southerly air flow from off the near continent” is bringing the warm conditions across the UK.
But it explained that “low pressure and associated fronts moving in from the south west” will bring “cooler and fresher conditions” by Friday, with heavy showers and thunderstorms possible.
Forecasters have issued three yellow weather warnings that thunderstorms could strike parts of the country on Wednesday and Thursday.
The first, running from 11am to 9pm on Wednesday and covering most of South West England and the south coast of Wales, warns of a chance that heavy rain and lightning bringing some disruption.
The Met Office said many areas will avoid the worst of the showers, but “thundery downpours” could bring 30mm and 50mm of rainfall in less than three hours in some places.
The other warnings, covering Northern Ireland, Wales and most of northern and central England, say thunderstorms could bring bring surface water flooding and disrupt travel between 11am and 8pm on Thursday.
Met Office deputy chief meteorologist Dan Harris said: “The hot and clear weather currently being experienced across large parts of the UK is forecast to break down through the middle of the week as showers and thunderstorms arrive.
“These will initially affect the southwest of the UK on Wednesday, before moving steadily north and developing across most areas through Thursday and Friday.”