England faces an unprecedented May heatwave, with temperatures forecast to hit 35C on Monday — a jump that would shatter the existing monthly record by a margin far wider than anything seen in modern meteorological history.
The Met Office confirmed that Monday is set to become the hottest May day on record in the UK, with highs of 35C expected. The current May record of 32.8C was set in 1922 and matched in 1944. If the forecast is realised, the new mark would exceed the old one by 2.2C — a dramatic leap given that records are typically broken by only a few tenths of a degree. A Met Office spokesperson described the heatwave as “unprecedented for the time of year.”
Sunday had already rewritten the record books. It was the UK’s hottest May day in at least 79 years, with Kew Gardens in west London recording 32.3C (90.1F). Monday is also expected to be the hottest bank holiday Monday on record. Overnight, a new May minimum temperature record was set: 19.4C at Kenley in Greater London, narrowly missing the threshold for a “tropical night” — defined as an overnight temperature that does not drop below 20C. Such a night has never occurred in May in the UK. However, forecasters predict two tropical nights on Monday and Tuesday, before temperatures ease on Wednesday.
The scale of the heatwave is not only about the daytime peak. The Met Office’s official heatwave criteria — three consecutive days above a local temperature threshold — have already been met in multiple locations. Santon Downham in Suffolk was the first to qualify on Sunday, with its threshold set at 27C. The other areas now officially in heatwave conditions are Heathrow, Kew Gardens and Northolt in London; Benson in Oxfordshire; Brooms Barn in Suffolk; and High Beach and Writtle in Essex. Each location has its own threshold based on the local climate — 28C for the London sites — meaning the event is widespread and sustained.
Why the heatwave is ‘unprecedented’ — and how scientists know
The word “unprecedented” is used carefully by meteorologists, and here it rests on solid statistical ground. The Met Office calculates that breaking the May record of 32.8C is now about three times more likely in the current climate than it would have been before the Industrial Revolution. An event that would have occurred once every 100 years in the pre-industrial era is now estimated to be a one-in-33-year occurrence. This shift is driven by human-induced climate change, which is making extreme heat events both more frequent and more intense.
The record-breaking margin is itself a measure of how unusual this is. The last time a monthly maximum record was broken in the UK was in January 2024, by 1.6C. The 40.3C recorded in July 2022 — the highest temperature ever seen in the UK — exceeded the previous record by 1.6C. A jump of 2.2C in May is therefore exceptional by any historical comparison. The UK generally experiences its hottest temperatures at the end of July or the beginning of August, making a record of this magnitude in late May all the more striking.
Temperatures of 30C or above in May are themselves rare, typically occurring only a handful of times since 1900 and usually separated by many years. The most recent such occurrence before this weekend was in 2012. Yet the long-term trend is clear: the three warmest springs on record in the UK have all occurred since 2017, and Europe is warming at twice the global average rate. According to the latest European State of the Climate report, Europe is the fastest-warming continent on Earth, with 2024 seeing above-average temperatures across at least 95% of the continent. This rapid warming is accelerating snow and ice loss and driving more frequent severe heatwaves, droughts, and record sea temperatures.
Heatwave extent and health warnings
Much of England has been affected. The UK Health Security Agency (UKHSA) has issued amber heat health alerts for the East Midlands, West Midlands, East of England, London, and the South East. These alerts indicate a risk of a rise in deaths, particularly among those aged 65 and over or with existing health conditions, and warn of increased demand on health and social care services. Age UK has advised older people to stay indoors between 11am and 3pm and to take regular cold baths or showers, and urged others to check on elderly relatives, friends, and neighbours.
The heat is also putting strain on infrastructure. Climate advisers have warned that the UK is “built for a climate that no longer exists” and urged the adaptation of schools, hospitals, and transport networks. High temperatures can cause rail tracks to buckle and roads to soften. At the Port of Dover, holidaymakers faced long queues during the bank holiday weekend, partly due to extra EU border checks under the new entry/exit system (EES), though the heat added to travel disruption.
Across the Channel, the heatwave is not confined to Britain. Large parts of western Europe are experiencing similar temperature peaks. The French national weather agency, Météo-France, has warned that periods of exceptional heat are set to become more frequent, premature, and intense. Europe endured its second most severe heatwave on record in recent years, and the longest and most severe July heatwave in sub-Arctic Fennoscandia saw temperatures exceeding 30C within the Arctic Circle. Warmer conditions are fuelling wildfires — over one million hectares have burned in Europe in 2025 — and droughts are worsening, particularly in southeastern Europe.
The role of El Niño — and a ‘super’ event on the horizon
More heatwaves are likely this summer as a “super El Niño” is expected to begin emerging. El Niño is a climate phenomenon characterised by the warming of the ocean surface in the central and eastern tropical Pacific Ocean. It is one of three states scientists monitor: La Niña (when sea surface temperatures are below average), neutral conditions (when they are about average), and El Niño. In its strong form, El Niño disrupts global weather patterns, and a “super” El Niño is defined by sea surface temperatures in a key stretch of the central Pacific rising more than 2C above normal. Such events have occurred only a handful of times in recorded history.
The 2015–2016 super El Niño caused catastrophic flooding in Peru, massive wildfires in Indonesia, and contributed to 2016 being one of the hottest years on record at that time. Scientists are concerned that climate change could make super El Niño events more common or more extreme. Some forecasts suggest the developing El Niño could be one of the most powerful in history, potentially exceeding the strongest events on record. This could push global temperatures more than 1.5C above pre-industrial levels in 2026 and 2027.
For the UK, strong El Niño events have previously been linked to an increased chance of colder and drier winters, while also disrupting global systems that can fuel heatwaves and extreme rainfall elsewhere. El Niño tends to weaken the Atlantic jet stream, potentially leading to warmer and drier weather across the UK, particularly in southern and central regions. Conversely, the north of England and Scotland may experience cooler and wetter conditions. The phenomenon can also strengthen storm systems. The full effects are expected to build up over the coming years, with the peak likely to hit in 2027, but the first signs are anticipated this summer — meaning the current May heatwave could be a precursor to what lies ahead.
The longest official heatwave on record in the UK remains the 15 consecutive days of July 1976. Whether this May event will approach that duration is uncertain, but the intensity and the early timing have already marked it as a milestone in a warming climate — one that scientists say is now three times more likely than it would have been without the emissions of the past two centuries.
