UK issues rare red heat warning as 40C temperatures loom

Large parts of England and Wales are preparing for potentially record-challenging heat this week, as a rare red warning for extreme temperatures is issued and forecasters say some locations could approach 40C.

Red alert as heatwave intensifies across England and Wales

Publicly available forecasts indicate that temperatures will climb sharply from midweek, with the highest values expected on Wednesday and Thursday across London, the Midlands, south-east Wales and southern England. The red warning is scheduled to run from 09:00 to 21:00 local time on both days, signaling a level of heat that is considered exceptional for the UK at any time of year, let alone June.

Latest projections suggest that many areas within the warning zone could see afternoon highs in the upper 30s, with some models indicating that 40C is possible in the hottest spots. Weather data shared in recent days shows growing confidence that the all-time UK June temperature record of 35.6C could be surpassed, with the broader heatwave described as both intense and unusually early in the summer season.

The red warning follows the expansion of earlier amber alerts that had already covered much of England and Wales. Those alerts have now been upgraded for the most affected regions, reflecting expectations of “widespread impacts” on health, infrastructure and transport, according to open guidance on the UK’s extreme heat alert system.

The current episode comes less than four years after the historic July 2022 heatwave, when the UK surpassed 40C for the first time on record. Analysts note that while the present outlook is still uncertain at the extreme end, there is now a realistic chance that some locations could again challenge that benchmark, particularly if humidity remains high and overnight temperatures fail to fall.

Travel networks brace for disruption and slower services

Transport operators across the country are preparing for possible disruption as tracks, roads and runways are exposed to prolonged extreme heat. Previous events, including the 2022 heatwave, led to widespread speed restrictions on rail services, buckling of rails in some locations and warnings against non-essential travel. Current public briefings suggest that similar measures may return if temperatures reach the upper levels now being forecast.

Rail passengers are being advised through operator announcements to expect slower journeys, short-notice alterations and the potential for cancellations on the hottest days. High temperatures can cause steel rails to expand and deform, overhead lines to sag and signalling equipment to overheat, all of which can force tighter safety margins and reduced line capacity. As a result, journeys that normally run to a frequent commuter timetable may be thinned out or merged to manage pressure on the network.

Road travel also faces strain when air temperatures climb toward 40C. Surface temperatures on untreated tarmac can climb much higher than the surrounding air, increasing the risk of softening, rutting and tar bleed. Highway authorities have previously deployed grit to some routes during severe heat to provide extra grip, and publicly available guidance suggests that drivers should be prepared for delays, congestion and breakdowns as vehicles and cooling systems are pushed to their limits.

Airports located within the red warning zone are monitoring runway conditions and passenger welfare arrangements as the heatwave develops. While commercial aircraft are designed to cope with high temperatures, very hot, still air can subtly affect take-off performance and turnaround times. Terminal operators are highlighting shaded waiting areas, hydration points and revised staff rotas to cope with busier early-morning and late-evening peaks as travellers adjust their schedules to avoid the hottest hours.

Health services and local authorities step up heat response

Health agencies have raised parallel heat health alerts, indicating that the incoming temperatures carry risks for the entire population, not only for those traditionally considered vulnerable. Previous research cited in public health reviews has linked periods of extreme heat in the UK with hundreds of additional deaths each year, with the burden falling hardest on older people, those with chronic illnesses and residents of poorly ventilated homes or care settings.

Care providers are receiving updated guidance reminding them to monitor indoor temperatures, increase checks on residents and ensure that drinking water is readily available at all times. During the July 2022 heatwave, mortality in some types of care settings was reported to have risen markedly when temperatures exceeded 40C, and recent commentary within the sector indicates that lessons from that episode are now being integrated into emergency planning.

Local councils in areas under red and associated health alerts are publicising simple protective measures such as closing curtains in sun-facing rooms, using fans responsibly, wearing light clothing and avoiding strenuous activity in the middle of the day. Community organisations are being encouraged through open communications to look out for isolated neighbours, particularly in high-rise buildings or top-floor flats, where “tropical nights” with temperatures staying above 20C can make recovery from daytime heat more difficult.

Hospitals and ambulance services are also revisiting surge plans that were developed after earlier extreme heat events. Publicly available preparedness documents describe contingency steps such as setting up cooled waiting areas, reinforcing staffing for urgent and emergency care, and working with local partners to direct the public toward non-emergency helplines and online advice in order to prevent services from becoming overwhelmed.

Impact on tourism, events and the visitor economy

The timing of the heatwave is reverberating through the UK’s visitor economy as attractions, accommodation providers and event organisers weigh whether to adjust schedules or capacity. Some outdoor events scheduled for midweek in the red warning area are already reviewing start times to move performances or matches out of the hottest part of the day. Guidance shared by venues in recent seasons points to earlier opening hours, shaded queueing areas and relaxed rules on bringing sealed water bottles as common adaptations during severe heat.

Urban destinations, particularly in London and other major cities, are likely to see a split response from visitors. While traditional sightseeing can become more challenging in near-40C conditions, city parks, riverside promenades and air-conditioned museums often experience spikes in demand as travellers seek cooler refuges. Tour operators are advising customers to plan indoor activities for early afternoon and shift walking tours to early morning or evening, where practical.

Coastal resorts and inland swimming spots may also see a surge in demand as people attempt to escape urban heat. Lifesaving and water safety organisations have repeatedly warned in public campaigns that high air temperatures can mask the dangers of much cooler water, which increases the risk of cold-water shock. As temperatures rise, local authorities around popular beaches, lakes and rivers are expected to increase signage, patrols and messaging about safe swimming areas and currents.

Accommodation providers across the warning area are fielding questions from guests about air conditioning, ventilation and cancellation policies. Many older hotels, guesthouses and short-let properties in the UK still rely on natural ventilation rather than full mechanical cooling, and some operators are now promoting portable fans, blackout curtains and access to shaded outdoor areas as part of their heatwave response to reassure both domestic and international visitors.

Climate signal and what this means for future UK summers

Climatologists have long highlighted that heatwaves are becoming more frequent, more intense and longer-lasting as the global climate warms. Educational material produced in partnership with UK meteorological services notes that the record-breaking July 2022 heatwave, during which the UK first exceeded 40C, would have been extremely unlikely without human-induced climate change. The prospect of approaching similar temperatures again so soon, and this time as early as June, is seen by researchers as part of a broader warming trend rather than an isolated anomaly.

Analyses of recent UK climate data indicate that average summer temperatures have been trending upward over the past few decades, while the number of very hot days has increased. Night-time minimum temperatures during heatwaves are also rising, limiting the body’s ability to recover and placing extra stress on vulnerable people and critical infrastructure such as power networks and transport systems.

Urban planners and local authorities are increasingly considering extreme heat as a core risk for British cities, alongside flooding and storm damage. Publicly available strategy documents discuss measures such as expanding tree cover, creating shaded streets, using reflective or permeable materials in new developments and designing buildings that do not overheat during prolonged hot spells. The latest red warning is expected to renew debate about how quickly these adjustments can be scaled up.

For travellers, tour operators and the wider tourism industry, the likelihood of more frequent extreme heat episodes is prompting a reassessment of when and how people explore the UK. Industry observers note that flexible booking policies, better heat communication and infrastructure designed for higher temperature peaks will all become increasingly important in keeping destinations attractive and safe during the height of summer.