Heat Index Calculator 🌡️
Calculate the apparent temperature based on air temperature and humidity.
Heat Index Comfort Levels (NOAA)
This table outlines the potential health impacts at different heat index values.
| Heat Index | Level | Potential Impact |
|---|---|---|
| 80°F - 90°F (27°C - 32°C) | Caution | Fatigue possible with prolonged exposure and/or physical activity. |
| 90°F - 103°F (32°C - 39°C) | Extreme Caution | Heat stroke, heat cramps, or heat exhaustion possible with prolonged exposure. |
| 103°F - 124°F (39°C - 51°C) | Danger | Heat cramps or heat exhaustion likely; heat stroke possible with prolonged exposure. |
| 125°F+ (52°C+) | Extreme Danger | Heat stroke is highly likely. |
Frequently Asked Questions
What is the heat index and why does it matter?
The heat index, or 'apparent temperature,' is what the temperature feels like when humidity is combined with air temperature. It's crucial because high humidity hinders the body's cooling process (sweating), increasing risks of heat-related illnesses.
How is the heat index calculated?
This tool uses the NOAA Rothfusz regression equation, a precise formula from the National Weather Service that considers multiple factors of temperature and humidity for accuracy, especially at high values.
What temperature & humidity ranges are used?
The formula is most accurate for temperatures ≥ 80°F (27°C) and humidity ≥ 40%. Below these values, the heat index is generally very close to the actual air temperature.
How do I interpret comfort levels and warnings?
The levels ('Caution', 'Danger', etc.) are based on NOAA guidelines and indicate the risk of heat-related illness with prolonged exposure. Higher levels signify a greater and more immediate danger.
Can this replace professional weather advisories?
No. This tool is for informational purposes only. It doesn't account for wind, direct sun, or personal health factors. Always rely on official local weather advisories for safety.
