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

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

The annual ‘State of the UK climate’ report for 2025, compiled by various expert organisations, paints a worrying picture. It highlights rising temperatures, an increase in extreme heat events, marine heat waves, and rapidly rising sea levels; all of which contribute to significant impacts on the country’s natural environment.

The report also warns of a “climate movement” in which warmer conditions migrate southward and cooler climates in the northern highlands decline. The assessment, which reflects a year of record heat and drought in 2025, comes as the UK experiences its third heatwave in as many months and underlines how human-caused climate change, driven primarily by the burning of fossil fuels, is intensifying extreme weather conditions.

The Met Office said 2025 was the UK’s hottest year on records dating back to 1884; This record was broken for the sixth time in the 21st century.

The report shows that the last four years have been among the five warmest years on record, with the last 10 years from 2016 to 2025 being 1.33 degrees warmer than the period from 1961 to 1990.

Mike Kendon, Met Office climate information scientist and lead author of the report, said the extreme temperature changes causing the biggest impact were particularly worrying.

The hottest day of the year is now 4.5 degrees warmer in some parts of the southeast than it was a few decades ago, and “35 degrees are expected at some point during the hot part of the summer,” he said, adding that such temperatures were relatively unusual in the 20th century.

The report shows that the number of days above 30 degrees in areas such as Greater London has quadrupled since the late 20th century.

“We are currently living in a time of historic and unprecedented change, and this evidence in terms of temperature across annual, seasonal, monthly and daily timescales suggests that the climate of the 20th century is no longer there.”

He said the UK’s climate was “literally on the move”, with new warmer conditions emerging in the south-east and northern highlands, losing the coldest habitats at the top of the mountains.

“Imagine this warming moving north and uphill; areas such as the Vale of York and Lancashire now have annual temperatures similar to those experienced by Greater London from 1961 to 1990,” he said.

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

Key observations for 2025 included the hottest spring and summer on record in the UK, 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 that most of England and Wales received less than half the average rainfall in spring, and in some places less than a third, with winter half-years over the last decade being wetter than in the past.

Sea levels around the UK have risen by around 20.1cm since 1901, but the rate of increase is accelerating.

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

The Woodland Trust said high seed yields were seen in 2025, particularly in gorse and oak trees, which is the “mast year” for acorns, possibly related to extremely hot, dry and sunny conditions between April and September.

Alex Marshall of the Foundation said: “There is a real cost to producing this much seed. Trees are depleted of their reserves, leaving them weaker and more exposed to the heat and dry conditions we have seen recently.”

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

RMS chief executive Professor Liz Bentley said the report, which comes after the first quarter of the 21st century, provides the “ground truth of climate change in the UK”, based 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, and we experience it through our weather,” he said, adding that the evidence in the report was “striking,” especially when looking at the extremes.

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

“This is something that people in the UK are already experiencing because of the weather conditions we’re experiencing, and even over the last few weeks we’ve been seeing this continue,” he warned, saying the report should help make more informed decisions about preparing for the climate Britons are currently living in.