london to roast in 27°c heat and sun before uk weather turns this weekend

Today isn’t quite as sweltering as only a few weeks ago (Picture: EPA)

London residents,don’t put your sunscreen away just yet – summer is back for one last hurrah.

September almost immediately brought an end to months of sunshine,blue skies and high temperatures.

But this was also a summer which saw four heatwaves,multiple hosepipe bans and health officials warning of ‘excess deaths’.

So,maybe a little bit of rain isn’t too bad.

Today,however,is different.

What is the weather in London today?

The Met Office has predicted a high of 27°C in London later in the afternoon – around 8°C above the seasonal average.

Temperatures in most parts of South East England are on the toasty side,reaching the low to mid 20s.

When the sun rises over London,the streets sparkle,cafe tables and chairs fill the sidewalks,and even Big Ben smiles. Walking down the street today,I didn't even mind the traffic jams because I was too busy enjoying this rare sunshine. ☀️🚶‍♀️ #LondonLife pic.twitter.com/mF6dUkwFvi

— Doreen (@BetaEspim) September 19,2025

By midday,it was already 25°C in the capital,with parks packed with sun-deprived locals.

‘When the sun rises over London,and even Big Ben smiles,’ a user on X said.

Another added: ‘Random hot day in London in September.’

If you’re more a pumpkin soup and cosy blankets type,Chris Bell,a senior meteorologist at the University of East Anglia’s WeatherQuest,knows exactly what you can blame for this one extra hot day.

To get the latest news from the capital visit Metro's London news hub.

The Met Office says London will reach a high of 26 or 27°C this afternoon (Picture: Metro)

‘The very warm temperatures today were brought by the combination of an area of low pressure developing to the southwest of Britain and high pressure located over central Europe,leading to a southerly flow of air from southern France and Spain,’ he tells Metro.

‘In those areas,it’s also been hot the last few days,temperatures there have reached into the low 30s in southern France and mid-to-upper 30s in Spain.

The jetstream,a band of strong winds blowing from west to east about 30,000 feet above the ground,is shoving warm air our way from the Caribbean and southern US,according to UK weather charts.

What will the weather be this weekend?

Jim N R Dale,a senior meteorologist at the British Weather Services,tells Metro that the mercury rising in September isn’t actually that unusual,nor is it quite a ‘heat bomb’ either.

Warm summer weather usually spills into September,with temperatures only dropping from the beginning of October.

‘This hot weather will be short-lived,ebbing away during Saturday,with temperatures of 15°C max by Sunday as winds turn to be from a northerly quarter,’ Dale adds.

‘Next week will be settled and mostly sunny but some chilly Autumnal mornings to come.’

When does autumn start?

Like many things in life,when autumn begins depends on who you ask.

Talk to a weather forecaster,and it’s already autumn. Meteorological autumn starts on September 1 and will conclude at the end of November.

Then there’s astronomical autumn,which will begin on September 22,according to the Met Office.

September,despite being the first month of autumn,is typically on the warm side (Picture: Jordan Pettitt/PA Wire)

This day is often called the autumn equinox,when Earth reaches a point in its orbit where the sun shines directly on the Equator.

From next Monday,our days will become shorter and the skies will darken sooner.

While astronomical autumn always starts in September,its date can shift every year. In 2023,for example,it started on September 23.

The same goes for when astronomy ends. It’ll end on December 21 this year,but it concluded two years ago on December 22.

These ever-changing cosmic events can give meteorologists and climate experts a bit of a headache,given the need for consistency to analyse weather trends every year,so they split the seasons into calendar months instead.