A wave of exceptional late-spring heat saw London sites top 35C and prompted transport limits, health alerts and warnings about open-water risks
The UK experienced an unusually strong spell of late-spring heat, with several monitoring sites reporting temperatures that beat the long-standing May records. Meteorological stations in and around the capital recorded readings above 35C, with Kew Gardens provisionally registering 35.1°C and Heathrow reaching around 35°C.
Other locations also reported high values, including Cardiff’s Bute Park at about 32.9°C. Forecasters described the event as an exceptional late-spring surge, noting both the daytime extremes and unusually warm nights that challenged routines and services across the country.
These extreme readings did not come without consequences. Rail operators and infrastructure managers imposed measures to protect passengers and equipment, while public-health bodies and emergency services issued warnings about heat-related risks and the dangers of swimming in cold open water.
The combination of high daytime temperatures and nights that stayed unusually warm created what meteorologists refer to as “tropical nights”, which complicate recovery from daytime heat and can increase health risks for vulnerable people.
How the records were set and where the heat hit hardest
Data from monitoring points showed successive breaches of the previous May maximum, which had been lower by several degrees. Until recently the May high stood near 32.8°C, but the latest observations exceeded that level on consecutive days by a significant margin. In London, Kew Gardens and Heathrow were prominent in the readings, and other urban and regional sites reported sustained warmth. Observers pointed out that this pattern — unusually high spring maxima alongside warm minima — is notable because such values were once rare even at the peak of summer. The Met Office emphasized the scale of the event and highlighted the role of persistent warm air masses in elevating temperatures across southern and central areas.
Immediate impacts on transport and public safety
Rail networks and operational responses
Infrastructure operators took precautionary steps to maintain safety on a hot track. Network Rail introduced a range of speed restriction measures where rails and signalling equipment were vulnerable to heat, slowing trains to reduce risk. As a result, a major regional operator warned that services across its network could be cancelled, delayed by up to an hour, or revised because of a mix of signalling faults, track defects and heat-related speed controls. Commuter and regional routes serving south-west London, the Home Counties and parts of the south-west were notably affected, with disruption expected through the busiest travel periods of the day.
Health alerts and warnings about water safety
Public-health authorities issued tiered heat-health alert messages for a broad swathe of England, with amber warnings focused on southern and central regions and yellow warnings covering parts of the north. The UK Health Security Agency (UKHSA) highlighted the increased health risks for older people and those with pre-existing conditions, urging the public to keep homes cool, avoid strenuous activity during peak heat and stay hydrated. At the same time, rescue and safety organisations raised the alarm about open-water dangers: despite high air temperatures, water remained cold in many rivers, lakes and quarries, increasing the risk of cold water shock. Lifesaving charities and fire authorities reminded families to supervise children and avoid unsupervised swimming following several recent fatal incidents linked to open water.
Forecast and outlook from meteorologists
Weather services warned that the heat would persist for several days before easterly or north-easterly breezes and low-pressure incursions bring cooler air and a higher chance of showers. Forecasters said the core of the warmth would shift geographically over the period, with southern areas continuing to register the highest nighttime temperatures — heightening the chance of further tropical nights — while northern districts would feel more of the daytime heat as the pattern evolved. Models indicate a gradual return toward more typical temperatures later in the sequence, alongside a rise in the likelihood of localized thunderstorms that may bring intense pulses of rain, lightning and gusty winds to parts of the country.
Practical advice and closing summary
Authorities urged people to take common-sense precautions: keep living spaces cool and shaded, avoid heavy exertion during the warmest hours, check on elderly or vulnerable neighbours, and heed transport guidance if travelling. Emergency services reiterated the specific hazard posed by inviting-looking open water, reminding the public that high air temperature does not make cold water safe. The recent spell underlined how early‑season heat can create significant disruption and risk, prompting a coordinated response from meteorological agencies, health bodies and transport operators to reduce harm while the unusual conditions persist.
