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Heatwaves
UK climate has shifted; 40°C is achievable. Heat-Health Alert system in place.
Context
The UK passed 40°C for the first time on 19 July 2022. Heat events are now Routine summer. The UKHSA's Heat-Health Alert (HHA) system runs through summer with green / yellow / amber / red tiers — amber means significant impacts on health services; red means widespread excess deaths likely.
When this matters
Heat-Health Alert at amber or red, or Met Office extreme heat warning.
Before
- Identify your coolest room — usually north-facing on the ground floor with curtains closed.
- Stock plenty of water — UK water mains pressure can drop in heatwaves as demand spikes.
- Plan to check on vulnerable people — over 75s, infants, anyone with cardiovascular or respiratory conditions, anyone living alone.
- Pets: never leave in a vehicle, ever. The UK average summer car interior temperature exceeds 50°C within 30 minutes.
- Wildfire risk: clear dead vegetation away from rural properties. Check garden BBQs are properly extinguished.
During
- Stay out of direct sun between 11:00 and 15:00. That's the peak UV + heat window.
- Drink water regularly, more than feels necessary — by the time you feel thirsty, you're already dehydrated.
- Avoid alcohol and caffeine during the hottest period — both worsen dehydration.
- Don't exercise hard outdoors during amber+ HHA hours.
- Watch for heat exhaustion (cool moist skin, weakness, nausea) and heatstroke (hot dry skin, confusion, collapse). Heatstroke is a 999 emergency.
- Wildfires: don't BBQ on dry moorland or heath, don't drop cigarettes, report smoke immediately.
After
- After amber+ HHA, check on neighbours within 24 hours of the alert ending — heat impacts on the elderly often manifest 24–48 h later.
- Heat exhaustion in a child — cool them, rehydrate, see a GP if symptoms persist beyond an hour.
- Wildfire damage: report to 999 if active fire or smoke, then to your local fire service for follow-up.
UK specifics — numbers, sources
- UKHSA Heat-Health Alerts: gov.uk/government/publications/heatwave-plan-for-england.
- NHS 111: heat-related illness advice.
- 999: heatstroke (collapse, confusion, hot dry skin) is an emergency.
- Wildfire reporting: 999.
- The 2022 UK heatwave caused an estimated 2,985 excess deaths. Heat is the most lethal UK weather hazard year-on-year.
Watch the data
Live chaseit feeds relevant to this hazard:
General guidance. Your specific circumstances may vary — follow the Met Office, Environment Agency / SEPA / NRW, your local council, and emergency services for situation-specific direction. See the code of conduct for chasers in the field.