Temperatures reach 20C to make it hottest day of 2025 so far

Thursday has become the hottest day of the year so far as temperatures topped 20C.

The Met Office said images show “plenty of blue skies across the UK, although high cloud in the west is making the sunshine hazy here” and “in the sunshine across the south temperatures have already reached 20C in a few spots”.

People basked in temperatures of 20.6C in Northolt, west London, beating the top figure this year of 19.7C in Crosby, Merseyside, on March 9.

It coincides with the spring equinox on Thursday, which has seen generally dry and fine weather with plenty of sunny spells.

The highest recorded UK spring equinox temperature was 21.5C in 1972.

Meteorological spring always starts on March 1 while astronomical spring, or the equinox, begins around March 20 each year.

The other equinox is in September and both mark the sun crossing the equator, rather than being at an angle.

Day and night are therefore about the same length.

The warm weather has also brought warnings of pollution and signs that those who are allergic to to birch pollen, a type of tree pollen from birch trees, may have tough times ahead.

A high air pollution alert has been issued for London, the first this year, after forecasters at Imperial College warned of a rise in particulate pollutants from mainland Europe.

London mayor Sir Sadiq Khan wrote on X, formerly Twitter: “I urge Londoners to look after themselves and protect those with conditions such as asthma. This includes refraining from engine idling and burning wood or garden waste.”

The Met Office’s UK pollen forecast manager, Yolanda Clewlow, said: “The pollen season has already started and people with a sensitivity to tree pollen may have noticed the early tree species in the air.

“For those who are allergic to birch pollen, the season for this species is likely to be high, largely due to the conditions last spring and summer when pollen was forming on some trees.”

Met Office meteorologist Aidan McGivern said “at 9.01am this morning, the spring equinox occurred, that means the northern hemisphere is now tilted towards the sun”, and it feels spring-like as “warmer air is dredged up from the south” around an area of low pressure.

More unsettled weather is ahead as “low pressure starts to move towards the UK, the winds will pick up, the cloud will build and we’ll see a change to more showery weather over the next few days”, he added in an online forecast.

A frost-free night is expected as the cloud and breeze builds up but sheltered parts of northern England and Scotland could see a touch of frost in the early hours.

A milder start to the day, compared with recent mornings, is expected on Friday, when it will be wetter in some places.

Mr McGivern said: “South-western parts of the UK will see showers from the word go, perhaps even a rumble of thunder, though showers will move into west Wales, Northern Ireland, western Scotland, through the day as well.”

In a marked change compared with the week so far it will become fairly breezy in the east and across higher parts of Scotland but “temperatures still above average” and it will still be “a warm day, but not quite as warm as Thursday”.