The United Kingdom broke its hottest May day on record on Monday, the Met Office confirmed, with Kew Gardens in west London provisionally reaching 34.8°C in the late afternoon, two full degrees above the previous May record of 32.8°C set in 1922 and matched in 1944. The reading is the highest daily maximum recorded during meteorological spring — March, April and May — since national records began in 1860.
Thirteen weather stations across southern and eastern England independently broke their own all-time May records on Monday, including Heathrow at 34.4°C, Northolt at 34.2°C, and St James’s Park at 34.0°C. The Met Office classified the broader event as a “historic heatwave” in its end-of-day summary, the first time the term has been used for a May event.
Tuesday, the second day of the late-May bank holiday, was forecast to remain hot through London and the south-east, with the Met Office suggesting the capital could reach 35°C and Norwich and Southampton both touching 34°C. Amber heat-health alerts — the second-highest tier — remained in place across most of England, with the UK Health Security Agency advising that vulnerable groups should be checked twice daily.
The cooling expected for Wednesday is sharp but uneven. A weak Atlantic front moving in overnight is forecast to bring temperatures down to the mid-20s across the south and the high teens across Scotland by Wednesday afternoon, though humidity will remain elevated until Thursday. The Met Office’s longer-range outlook now expects above-average temperatures to persist through the first week of June.
The heat has already pressed against parts of the country’s infrastructure. Network Rail imposed speed restrictions on several lines south of the Thames for the second day running on Monday, citing buckled rail risk; Heathrow operated with reduced runway capacity through the afternoon as the airfield surface temperature exceeded operating limits. The London Fire Brigade declared a major incident shortly after 4 p.m. as grass fires spread across Walthamstow Marshes and at Mitcham Common.
On the demand side, the National Grid Electricity System Operator said peak demand on Monday afternoon had jumped above forecast, with air-conditioning load now — unusually — a non-negligible share of UK domestic consumption. Power prices on the day-ahead market touched £180/MWh during the early evening peak, the highest mid-week May reading since 2022.
Scientists at the UK Met Office’s Hadley Centre said attribution work on Monday’s record would take several weeks but that climate-change signals in May-time heat extremes had become “unambiguous” over the past decade. “Two degrees above the previous all-time May record is not a statistical accident,” a senior climate scientist said in a briefing call. “This is the new operating envelope.”