When does summer 2025 start, according to the Met Office after UK's warmest spring on record
Summer 2025 officially begins on Saturday, 21 June, according to the astronomical calendar, marking the summer solstice and the longest day of the year.
But meteorologists consider the first day of summer to be June 1, based on seasonal averages that divide the year into four equal parts.
The Met Office says: “However, meteorologists are also interested in the beginning of the meteorological summer. Meteorological summer will always begin on 1 June; ending on 31 August.
“The meteorological seasons consist of splitting the seasons into four periods made up of three months each. These seasons are split to coincide with our Gregorian calendar, making it easier for meteorological observing and forecasting to compare seasonal and monthly statistics.
“The seasons are defined as spring (March, April, May), summer (June, July, August), autumn (September, October, November) and winter (December, January, February).”
This comes as the UK has just experienced its warmest spring on record, with the Met Office confirming that spring 2025 has surpassed all historical records for temperature and sunshine since records began.
According to the Met Office: “The UK, and all four nations, have all recorded their warmest spring for mean temperature since the series began in 1884, surpassing the previous record from 2024.”
This spring's mean temperature reached 9.5°C, exceeding the long-term average by 1.4°C. In addition to being the warmest, it was also the sunniest spring on record for the UK, Northern Ireland, Scotland, and Wales, with England recording its second sunniest since sunshine records began in 1910.
The exceptional season began with a record-breaking March, followed by April 2025 becoming the UK’s sunniest April on record, and May ranking as the second sunniest May ever recorded.
Daytime temperatures were especially remarkable. The UK recorded a maximum daytime temperature of 14.6°C, smashing the previous record of 14.0°C set in 1893.
“All four nations also recorded their highest spring mean temperature, with Northern Ireland and Scotland recording notably high temperatures, up 1.6°C on average,” the Met Office added. “For Northern Ireland, this meant surpassing the previous long-standing warmest average spring temperature, set back in 1893.”
The spring also saw a marine heatwave, with sea surface temperatures up to 4°C above normal, creating unprecedented conditions along UK coastlines.
With 653.3 hours of sunshine, a 43% increase over the seasonal average, Spring 2025 eclipsed the previous sunshine record set in 2020 by more than 27 hours. Scotland, Wales, and Northern Ireland all recorded their sunniest springs ever.
As the country transitions into summer, forecasters say the trend of warmer and sunnier seasons may continue, highlighting growing evidence of climate change. “Eight of the ten warmest UK springs have occurred since the year 2000,” the Met Office noted, “and the three warmest springs have all occurred since 2017.”