According to the Met Office, the hot weather in the southern part of the UK is expected to continue for the rest of the week.
As Thursday started warm and humid – with some fog in the east – the Met Office said temperatures across the UK will rise throughout the day under largely sunny skies.
Temperatures in the south are expected to reach or exceed 30C, with London preparing to hit a high of 32C around 4pm on Thursday.
Temperatures reached 32C in Kew Gardens on Wednesday. This made it the hottest September day in the UK since 2016 and just 0.2°C shy of the hottest day of the year.
There could be isolated heavy or thundery showers later in the west of the country, but the hot weather is expected to last until the weekend.
Met Office chief meteorologist Paul Gundersen said: “There is an area of high pressure in the southeast of the UK, bringing calmer conditions and temperatures well above average for the time of year.”
“While the highest temperatures are expected in the south, heatwaves are expected across much of England and Wales, particularly parts of Scotland and Northern Ireland, with unusually high temperatures also expected in parts of Scotland and Northern Ireland.”
September’s heatwave is expected to peak on Saturday, with temperatures rising to up to 33C in London, the Met Office said, although it will be cooler further north.
That would make it the hottest day of the year, topping 32.2C in June, with the UK health agency issuing a yellow heat warning until 9pm on Sunday evening.
This means the impact of the weather is likely to be felt across the healthcare system, with people over 65 or those with pre-existing respiratory or cardiovascular conditions at higher risk.
Although temperatures have already risen this high in September, it is unusual for the heat to last this long, with the Met Office predicting five to six days above 30°C for some areas.
Even in the south there is the possibility of tropical nights with temperatures above 20 °C.
The heatwave is being driven by tropical storms pushing a high-pressure system over the UK, with the jet stream having moved north and bending into a so-called Omega blocking pattern.
Named after the Greek letter Omega because of its shape, this system forms when a high pressure area gets stuck between two low pressure areas to the west and east and slightly to the south.
This has caused torrential rain and flooding in Spain and Greece, but hot, dry and clear conditions in the UK and central Europe.
Neil Armstrong, chief meteorologist at the Met Office, said: “An active tropical cyclone season in the North Atlantic has helped to strengthen the pattern over the North Atlantic by pushing the jet stream well to the north of the UK, pulling very warm air northwards could.” .
“It is a marked contrast to much of the meteorological summer, when the UK was on the northern side of the jet stream, with cooler air and more unsettled weather.”
The Met Office defines a heatwave as three consecutive days in a given region exceeding a certain threshold, which varies across the UK.
For Scotland, Wales, Northern Ireland, Cornwall and northern England the limit is 25°C; for Somerset, Hampshire and the Welsh Borders, 26th century; the South Coast, East Anglia and the East Midlands, 27th century; and for London and the Home Counties the threshold is 28°C.
https://www.standard.co.uk/news/environment/london-uk-weather-forecast-record-september-metoffice-bbc-b1105410.html The hot weather continues as the temperature in London reaches 32°C