What Is the Heat Index?
The heat index (or apparent temperature) shows what the temperature feels like when humidity is factored in. At 33°C with 70% humidity, the heat index can reach 41°C — well into the danger zone.
Why It Matters
Your body cools itself by sweating. When humidity is high, sweat cannot evaporate efficiently, and your core temperature rises. The heat index captures this effect.
Heat Index Danger Scale
| Heat Index | Risk Level | Symptoms |
|---|---|---|
| 27-32°C | Caution | Fatigue possible with prolonged exposure |
| 33-39°C | Extreme Caution | Heat cramps, exhaustion possible |
| 40-51°C | Danger | Heat exhaustion likely, heat stroke possible |
| Above 51°C | Extreme Danger | Heat stroke highly likely |
Heat Index Table
| Temp \ Humidity | 40% | 50% | 60% | 70% | 80% |
|---|---|---|---|---|---|
| 27°C | 27°C | 27°C | 28°C | 29°C | 30°C |
| 30°C | 30°C | 31°C | 33°C | 35°C | 38°C |
| 33°C | 34°C | 36°C | 38°C | 42°C | 48°C |
| 36°C | 39°C | 42°C | 47°C | 54°C | — |
Staying Safe
- Hydrate before you feel thirsty — thirst means you are already dehydrated
- Take breaks in shade or air conditioning every 30 minutes
- Wear light, loose, light-coloured clothing
- Check on elderly neighbours and pets
- Never leave children or animals in parked cars
Check the feels-like temperature on Weather Tomorrow.
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