1. What is a Heat Index Calculator?

Definition: This calculator estimates how hot it feels when relative humidity is combined with air temperature.

Purpose: It helps assess heat risk for outdoor activities, workplace safety, and health precautions.

2. How Does the Calculator Work?

The calculator uses the Rothfusz regression formula:

Where:

• \( HI \) — Heat index (°F)
• \( T \) — Temperature (°F)
• \( RH \) — Relative humidity (%)
• \( c_1 \) to \( c_9 \) — Regression coefficients

Explanation: The formula approximates how the human body perceives temperature when humidity affects the body's ability to cool itself.

3. Importance of Heat Index Calculation

Details: The heat index helps prevent heat-related illnesses by indicating when extra precautions are needed.

4. Using the Calculator

Tips: Enter temperature in °F (must be ≥80°F) and relative humidity in % (must be ≥40%). The formula is only valid for these ranges.

5. Frequently Asked Questions (FAQ)

Q1: Why does humidity affect how hot it feels?
A: High humidity reduces sweat evaporation, the body's primary cooling mechanism.

Q2: What's considered a dangerous heat index?
A: 90-105°F: Caution; 105-130°F: Extreme caution; >130°F: Danger of heatstroke.

Q3: Why doesn't the calculator work below 80°F?
A: Humidity has minimal effect on perceived temperature in cooler conditions.

Q4: Are there different formulas for heat index?
A: This is the standard NWS formula. Some use simplified versions for limited ranges.

Q5: How accurate is the heat index calculation?
A: It's an approximation - actual perception depends on individual factors and conditions.