Heatwave
Dangerous stretches of extreme heat
What is it?
A heatwave is a prolonged period of abnormally hot weather relative to what a location is used to. Heat is one of the deadliest weather hazards because its effects build silently over hours and days.
How we measure it
Forecast daytime maximum temperature (°C) from Open-Meteo; the engine flags escalating severity as daily highs cross heat-stress thresholds.
Daytime high — heat-stress guide
- < 32°CComfortable–warmNormal summer conditions for most regions
- 32–38°CCautionFatigue and cramps possible with prolonged exposure
- 38–41°CDangerHeat exhaustion likely; heatstroke possible
- > 41°CExtreme dangerHeatstroke risk with continued exposure
Within safe range
Below ~32°C a healthy, hydrated body sheds heat effectively through sweating, provided you drink water and rest in shade periodically.
Beyond the range
Beyond ~38°C — especially with high humidity, which blocks sweat evaporation — core temperature can climb faster than the body can cool. Heat exhaustion (dizziness, nausea, heavy sweating) can progress to heatstroke, a medical emergency where the body's cooling fails entirely. Night-time heat above ~25°C prevents recovery and multiplies risk over consecutive days.
Precautions
- Drink water regularly — thirst lags dehydration.
- Shift exertion to early morning; rest 12–4 pm.
- Never leave children or pets in parked vehicles — interiors gain ~10°C in 10 minutes.
- Check on elderly neighbours daily during multi-day events.
- Loose light clothing, cool showers, and the coolest room of the house at night.
- Heatstroke signs (confusion, hot dry skin, collapse) → emergency services immediately.