UK Braces for 40C Heat Dome - Red Warning, Hundreds of Schools Close
Rare Met Office red alert Wed-Thu. June record under threat. Army cancels ceremonies, trains cut services.
Britain went from lightning floods to a furnace in 48 hours.
After an overnight thunderstorm on June 23, the Met Office issued a red extreme heat warning for Wednesday and Thursday - only the second time such an alert has been used for heat. Temperatures could hit 40C in parts of England and Wales.
Welcome to the heat dome.
What the red warning means
The alert runs 09:00 BST Wednesday to 21:00 BST Thursday, covering London, the Midlands, southern England, and south-east Wales.
Forecasters warn of:
- temperatures up to 40C in the worst-hit areas
- high humidity making it feel even hotter
- “tropical nights” - little cooling after dark
- severe health risks beyond the usual vulnerable groups
- major travel disruption
The UK Health Security Agency issued its own red heat health alert - also only the second ever. It covers the West Midlands, East Midlands, South East, South West, London, and East of England from 01:00 Wednesday to 23:00 Thursday.
Schools shutting down
There is no legal maximum classroom temperature in the UK. Head teachers decide.
Hundreds of schools are closing fully or sending pupils home early:
| Region | Scale |
|---|---|
| Somerset | ~100 schools closed Wed-Thu |
| Buckinghamshire | ~100 partially closed |
| Gloucestershire | ~86 affected |
| Hampshire | 35+ listed |
| London (Sutton, Haringey) | multiple closures Tue-Thu |
| West Sussex (Horsham) | early finish Wed-Thu |
Tanbridge House (~1,500 pupils) and The Forest School in Horsham are among those shutting doors. St John’s Marlborough in Wiltshire closes Tue afternoon and all day Wed-Thu.
Parents face a childcare crisis on top of the heat.
Transport and public life
- National Rail and Eurostar - cancellations and delays
- Great Western Railway - “essential travel only” Wed-Thu
- South Western Railway - heat alerts through Thursday
- Army - ceremonial operations cancelled in London and Windsor
- Mayor of London - high air pollution alert triggered
Older train fleets struggle in extreme heat - engines and cooling systems fail. The same infrastructure that melted under July 2022’s 40.3C record is being tested again - in June.
How hot is this really?
- June record: 35.6C (Hampshire, 1976) - likely to fall
- UK all-time high: 40.3C (July 2022) - forecasters say June could come close
- Kew Gardens painted a drought-killed oak red to highlight climate impact
The Met Office says human-driven climate change makes extreme heat events more likely. Critics argue UK buildings, schools, and railways were never built for this.
After the storm
June 23 brought nearly 3,000 lightning strikes and flooded Elizabeth Line tunnels. June 24-25 brings the opposite extreme.
Londoners who thought the midnight storm was wild are about to discover that silence at 38C can be worse than thunder.
Stay hydrated. Check on elderly neighbours. And if your kid’s school texted at 6am - you are not alone.