A thermometer at Kew Gardens in southwest London climbed to 32.3 degrees Celsius on Saturday, making it the hottest May day recorded anywhere in the United Kingdom since 1944. Two days later, the same station may have obliterated that benchmark entirely: the Met Office reported a provisional reading of 35.1 degrees Celsius on May 26, a figure that, if verified, would smash the longstanding national May record by more than two degrees.
The heat is not confined to Britain. Across Spain, Portugal, and southern France, temperatures have been running 12 to 16 degrees Celsius above the seasonal average, according to anomaly data from the Copernicus Climate Change Service. Forecast models suggest the pattern will hold through the first weekend of June, raising alarms over wildfire risk, crop stress, and public health across a wide swath of western Europe.
Saturday’s spike and what came next
The 32.3-degree reading at Kew on Saturday was striking on its own. The UK’s all-time May record, 32.8 degrees Celsius, was set on 29 May 1944 at both Horsham and Tunbridge Wells in southeast England and is documented in the Met Office’s official climate extremes table. That mark was also matched in 1922. Nothing in the 80 years since had come as close as Saturday’s value.
Then Monday’s reading at Kew blew past it. The provisional 35.1 degrees Celsius would not just edge the old record but vault over it by 2.3 degrees, a margin that is enormous by the standards of national temperature records, where new marks are typically set by tenths of a degree.
The Met Office has stressed that the figure remains provisional. Ratifying a new UK record requires checks on instrument calibration, station siting, maintenance logs, and whether nearby heat sources could have influenced the sensor. Only after that review will the number be formally accepted, adjusted, or rejected. For now, the official May maximum remains 32.8 degrees Celsius.
A continental heat dome
The engine behind the heat is a large, slow-moving high-pressure ridge that has buckled the jet stream into a pattern meteorologists call an omega block, named for its resemblance to the Greek letter. The configuration acts like a conveyor belt, pulling scorching air from the Sahara and the western Mediterranean northward across Iberia, France, and into the British Isles. Because the ridge stalls rather than drifting east, heat accumulates day after day under cloudless skies and near-calm winds.
Copernicus reanalysis maps, which blend satellite, weather-balloon, and surface observations into gridded temperature fields against a 1991-2020 baseline, show the most extreme departures over central and southern Spain, inland Portugal, and the Garonne and Rhone valleys of France. Anomalies of 12 to 16 degrees above the May average place this event far outside the normal late-spring distribution for southwestern Europe, where daytime highs in late May typically sit in the mid-20s Celsius, not the high 30s.
National weather services in Spain and Portugal have not yet published station-level daily breakdowns for this episode in the sources reviewed for this article. It is likely that several local May records have fallen across Iberia, but confirming that will require data releases from AEMET in Spain and IPMA in Portugal in the coming days.
Why persistence matters more than peaks
A single hot afternoon is one thing. Multiple consecutive days of extreme heat are another. The UK Met Office confirmed that heatwave thresholds, which require sustained elevated temperatures over several days, were crossed in multiple regions during this episode. Overnight lows were also unusually high, a detail that matters because the human body relies on cooler nighttime temperatures to recover from daytime heat stress.
Across southern Europe, the persistence of the ridge has compounded risks that a brief spike would not. Soils that were already drying after a warm spring have lost further moisture, raising wildfire danger across Mediterranean scrubland and forest. River levels have dropped, potentially constraining water availability for irrigation and for cooling intake at thermal and nuclear power plants. Energy grids face rising demand from air conditioning at the same time that some generating capacity may be curtailed.
Agricultural analysts are watching closely. Crops in sensitive growth stages, particularly cereals heading toward harvest in Iberia and soft fruit in southern France, are vulnerable to heat shock. Comprehensive yield-loss assessments typically emerge only after an event, once national agricultural agencies compile field data, but early reports from farming regions suggest stress is already visible.
Putting it in climate context
For the UK specifically, the potential new May record would sit well below the absolute national temperature record of 40.3 degrees Celsius, set at Coningsby in Lincolnshire on 19 July 2022. But comparing May and July readings misses the point. What makes a May temperature of 35 degrees remarkable is how far it sits from what the atmosphere has historically been capable of producing at that time of year. The sun angle, soil moisture, and sea-surface temperatures of late May are fundamentally different from those of mid-July, which is why the existing May record had stood for eight decades while summer records have been broken more frequently.
Climate scientists have documented a clear trend toward more frequent and more intense European heatwaves, driven by rising global temperatures. Attribution studies, including work published through the World Weather Attribution initiative, have repeatedly found that events like this are made significantly more likely and more severe by human-caused climate change. A formal attribution analysis for this specific episode has not yet been published, but the broader scientific framework leaves little doubt about the direction of the trend.
What to watch in the days ahead
Three things will determine how this story develops. First, the Met Office verification of the 35.1-degree provisional reading at Kew: confirmation would rewrite UK climate history for May, while rejection would still leave the 32.3-degree Saturday reading as the closest approach to the 1944 record in eight decades. Second, station-level data releases from AEMET, IPMA, and Meteo-France will clarify whether national May records have also fallen across Iberia and France. Third, the behavior of the ridge itself: forecast models as of late May 2026 favor continued warmth into the first days of June, but any westward shift in the blocking pattern or an earlier intrusion of Atlantic air could bring relief sooner than expected.
For the millions of people living under this heat dome, the forecast offers little immediate comfort. Health authorities across the affected countries have urged residents to stay hydrated, avoid outdoor exertion during peak afternoon hours, and check on elderly neighbors. Whether or not every provisional number survives verification, the scale and persistence of this late-spring heat event have already made it one of the most significant meteorological stories in Europe so far in 2026.
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*This article was researched with the help of AI, with human editors creating the final content.
