Heat Index Calculator
—
Heat Index Categories
| Heat Index | Category | Possible effect |
|---|---|---|
| 80–89°F 26.7–31.7°C | Caution | Fatigue possible with prolonged exposure or physical activity. |
| 90–102°F 32.2–38.9°C | Extreme Caution | Heat cramps or heat exhaustion possible; heat stroke may occur with prolonged exposure or activity. |
| 103–124°F 39.4–51.1°C | Danger | Heat cramps or heat exhaustion likely; heat stroke possible with prolonged exposure or activity. |
| ≥125°F ≥51.7°C | Extreme Danger | Heat stroke highly likely. |
About: Heat index estimates how hot conditions feel when air temperature and relative humidity are combined.
Method: Uses the U.S. National Weather Service procedure: a Steadman-based initial estimate followed, where appropriate, by the Rothfusz regression and official humidity adjustments.
Important: Heat-index values assume shaded conditions with light wind. Direct sunlight can increase apparent heat by up to about 15°F (8°C).
Reference: U.S. National Weather Service — Heat Index
Current weather: With your permission, your browser provides coordinates and Open-Meteo supplies current air temperature and relative humidity for that location.