The United Kingdom experienced its warmest and sunniest year since records began in 2025, a landmark double record-breaker fuelled by what scientists describe as “exceptionally high” sea surface temperatures. The figures, released by the Met Office, underscore a rapidly changing climate where marine heatwaves are increasingly locking in warmth across the British Isles. 

Data released in a statement by the Met Office confirms that the provisional annual average temperature for the UK was 10.09°C. This surpassed the previous record of 10.03°C set in 2022 and marks only the second time the national mean has exceeded the 10.0°C threshold. Simultaneously, 2025 became the sunniest year on record with 1,648.5 hours of sunshine, beating the 2003 record by more than 60 hours. 

A critical factor in this year’s data was the unprecedented state of the waters surrounding the UK. Dr Ségolène Berthou, an air-sea interaction specialist at the Met Office, stated that the seas were “consistently amongst the warmest on record during 2025,” with marine heatwave conditions persisting for almost the entire year. This “exceptional” spring warming allowed the ocean to heat up nearly a month ahead of schedule, preventing the air from cooling as it normally would. 

Climate scientists view these results as a clear signal of human-induced climate change. Dr Mark McCarthy, the Manager of the Met Office National Climate Information Centre, said that while natural variability plays a role, the record-breaking warmth “is consistent with the warming we expect to see as a result of human-induced climate change.” He noted that all ten of the UK’s warmest years have now occurred within the last two decades. 

The impact of these record temperatures and sunshine levels was felt across the country. As reported by the BBC, a series of four summer heatwaves sent temperatures above 35°C in some areas, contributing to the UK’s warmest spring and summer on record. However, as noted by Sky News, it was the “longevity” of the heat rather than extreme daily peaks that defined 2025, with every month except January and September being warmer than the long-term average. 

The high sunshine totals also provided a significant boost to the energy sector. As reported by The Guardian, the exceptional levels of solar radiation helped renewable energy records fall, though experts warned the heat also placed stress on biodiversity and water resources. 

Despite the sun and warmth, the Met Office warned that these shifting baselines present new risks. Permanent marine heatwave conditions could become a reality by the middle of the century if global emissions are not curtailed. Experts have stated that by 2050, a year as warm as 2025 could be considered a standard or even “cool” year relative to future norms.