Schools and Transport Brace for Extreme Heat
Hundreds of schools have arranged for at least partial closures, and several train operators, including the UK's largest, have advised against non-essential travel as temperatures rise sharply.
The highest temperature recorded on Tuesday was 34.66C in Wisley, Surrey. Northern Ireland and Scotland experienced their hottest days of the year, reaching 28.16C and 296C respectively, while Wales recorded a peak of 32.26C.
The heatwave is expected to intensify, with forecasts predicting temperatures around 37 to 386C in southern England on Wednesday.
Red Extreme Heat Warning Issued
A red extreme heat warning has been declared for parts of England and Wales from Wednesday morning until Thursday evening, indicating a danger to life.
The Met Office stated that from 09:00 BST on Wednesday to 21:00 on Thursday, an exceptional period of hot and humid weather will affect parts of south and central England and south Wales.
Temperatures as high as 396C in southern England on Wednesday are possible.
High humidity will exacerbate discomfort; for example, an air temperature of 356C may feel like 416C.
The forecaster warns of risks including serious illness or danger to life in affected areas. There is also a likelihood of power outages and disruption to essential services such as water due to heat-sensitive system failures.
Increased visits to coastal areas, lakes, and rivers are expected, raising the risk of water safety incidents.
The UK's June temperature record of 35.66C set in 1976 is likely to be surpassed, though maximum temperatures will remain below the all-time high of 40.36C recorded in 2022.
Temperatures on Tuesday were about 26C to 36C lower than forecast in southeast England due to overnight intense rainfall and flash flooding in some areas.
Nighttime temperatures will also remain elevated this week, with some locations not dropping below 206C, resulting in so-called tropical nights.
Health Alerts and Expert Warnings
The UK Health Security Agency (UKHSA) has issued a red heat health alert from 01:00 on Wednesday until 23:00 on Thursday.
Prof Robin May, chief scientific officer at the UKHSA, said this was only the second time the red heat health warning had been issued, the previous occasion being July 2022.
Speaking on BBC Radio 4's Today programme, he said the warning "signals a very widespread threat" from the heat, including risks "to people who generally think of themselves as not being particularly threatened by heat".
"Often we are warning about the vulnerable, the elderly, the young, but in this case we're also warning otherwise healthy people in their prime of life to take very cautious steps, because this heat is going to be quite intense and can have very serious life threatening effects even in people who are completely fit," he said.
Matthew Hopkins of the acute and ambulance network for the NHS alliance told the Today programme that he expected emergency service demand to rise over the coming days during the extreme heat period.
School Closures and Adjustments
More than 300 schools across England and Wales plan to be partially or fully closed on Tuesday and later in the week due to the heat.
Some schools will close early on Wednesday and Thursday to protect children from the heat, with pupils permitted to wear PE kits instead of full uniforms on those days.
The Department for Education usually does not advise school closures but provides guidance on managing high temperatures.
Travel Disruptions Expected
The Met Office has warned of travel disruptions for car, rail, and air travelers.
Passengers on the National Rail network have been urged to avoid non-essential travel and to carry water.
GTR, the UK's largest train operator, announced it will suspend the Gatwick Express from early afternoon on Wednesday and Thursday, though services to the airport will continue via Thameslink and Southern trains.
Safety speed restrictions will be imposed over the next two days, reducing train frequency on Thameslink, Great Northern, and Southern lines.
GTR passengers can obtain refunds for tickets purchased for Tuesday and the following days if they decide not to travel.
Avanti West Coast will operate fewer services from Tuesday to Thursday, and Chiltern Railways has cut its services by more than half during this period.
National Rail explained that heat can cause overhead lines to expand and rails to buckle.
The RAC anticipates a significant increase in breakdown assistance requests as temperatures peak, noting it is already handling 10% more breakdowns than usual for this time of year.
Public Events and Warnings
Ceremonial guard changes in London and Windsor have been cancelled on Tuesday, Wednesday, and Thursday to reduce risks to military personnel, horses, and the public.
Amber weather warnings remain in effect until Thursday for parts of south and central England and Wales.
Thunderstorms and Lightning Strikes
Tuesday's hot and humid conditions were preceded by thunderstorms in the early hours, with approximately 29,000 lightning strikes recorded in the south, according to the Met Office.
The storms caused flash flooding and travel disruption in parts of England, with the London Fire Brigade responding to 400 calls overnight.
Emergency services reported that two house fires in London and one in Bristol were believed to have been caused by lightning strikes.
Power outages affected hundreds of homes in southwest England on Monday evening, as reported by the National Grid.
Cause and Climate Context
The heatwave is caused by a "heat dome," a high-pressure area that becomes stationary, trapping warm air beneath it.
While attributing individual extreme weather events directly to climate change is challenging, scientists agree climate change increases the frequency and intensity of heatwaves.
Over the past 30 years, Europe has warmed by 0.566C per decade, according to the Copernicus climate service, intensifying heat extremes.
The United Nations warned on Thursday that global average temperatures are likely to remain at or near record levels this year and for the next four years.
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