UK’s 20th century climate ‘now gone’ amid warning extreme temperatures are new normal

The UK’s 20th-century climate is “now gone,” with what were once considered extreme conditions increasingly becoming the norm, according to a stark assessment from the Met Office.

The annual “state of the UK climate” report for 2025, compiled by various expert organisations, paints a concerning picture. It highlights escalating temperatures, a surge in extreme heat events, marine heatwaves, and rapidly rising sea levels, all contributing to significant impacts on the nation’s natural environment.

The report also warns of a “climate on the move,” where warmer conditions are migrating into the south while the colder climates of the northern uplands diminish. This assessment, reflecting the record hot and drought-stricken year of 2025, arrives as the UK experiences its third heatwave in as many months, underscoring how human-caused climate change, primarily driven by fossil fuel combustion, is intensifying extreme weather patterns.

The Met Office said 2025 was the UK’s warmest year in records dating back to 1884 – the sixth time the record has been broken in the 21st century.

The last four years have all been among the top five warmest on record, and the latest 10 years from 2016 to 2025 were 1.33C warmer than the period from 1961 to 1990, the report shows.

Mike Kendon, Met Office climate information scientist and lead author of the report, said changing temperature extremes – which cause the greatest impact – were particularly concerning.

The hottest day of the year is now 4.5C warmer than it was a few decades ago in parts of the south east, and “we are coming to expect 35C at some point in a hot spell in summer”, temperatures that were comparatively unusual in the 20th century, he said.

The number of days over 30C has quadrupled in areas such as Greater London since the late 20th century, the report shows.

“We are right now living in a time of historic and unprecedented change and in terms of temperature, on annual, seasonal, monthly and daily timescales, this evidence shows climate of the 20th century has now gone.”

He said the UK’s climate is “on the move, literally”, with new warmer conditions emerging in the south east and northern uplands losing the coldest habitats from the tops of mountains.

“Think of this warming as moving north and uphill, with areas like the Vale of York and Lancashire now having similar annual temperatures to those experienced by Greater London in 1961 to 1990,” he said.

The report was led by the Met Office, with contributions from the UK Centre for Ecology and Hydrology, National Oceanography Centre and the Woodland Trust’s Nature’s Calendar, which provides evidence of the changing seasons.

Key observations from 2025 show the year included the UK’s warmest spring and summer on record, a record 297 marine heatwave days in the seas around the UK, and the sunniest year in a series dating back to 1910.

It also showed most of England and Wales received less than half the average rainfall in spring, and some places had less than a third, while the winter half-years in the last decade have been wetter than in the past.

Since 1901, the sea levels around the UK have risen by about 20.1cm but the rate of rise is accelerating.

Storm surges in 2025 had a limited impact as they occurred on small or moderate tides, but if Storm Eowyn, which hit in January last year, had occurred a week later on a spring tide, it could have been a one in 300-year event at Heysham, Lancashire, the NOC said.

And 2025 saw high seed yields, likely associated with the extreme warm, dry and sunny conditions between April and September, the Woodland Trust said, particularly in blackthorns and oaks – which had a “mast year” of acorns.

The trust’s Alex Marshall said: “Producing this much seed comes at a real cost. Trees exhaust their reserves, leaving them weaker and more exposed to the heat and recent dry conditions we’ve been seeing.”

The annual assessment is published in the Royal Meteorological Society’s (RMS) International Journal of Climatology.

RMS chief executive Professor Liz Bentley said the report – coming after the first quarter of the 21st century – provided “the ground truth of climate change in the UK”, built on decades of high quality weather observations.

“Climate change is often discussed in terms of global averages or projections decades ahead.

“But for most people, climate change is much closer to home, and we experience it through our weather,” she said, adding the evidence in the report was “striking”, particularly when looking at the extremes.

“Climate change is no longer an abstract concept for future generations,” she said.

“It’s something that people across the UK are already experiencing through the weather that we live, and we’re seeing that even playing out the last few weeks,” she warned, saying the report should help make better-informed decisions about preparing for the climate Britons are now living in.