1. What is Heat Index?

Definition: The heat index (HI) is a measure that combines air temperature and relative humidity to determine the human-perceived equivalent temperature.

Purpose: It indicates how hot it feels when humidity is factored in with the actual air temperature.

2. How Does the Calculator Work?

The calculator uses the Rothfusz regression equation:

Where:

• \( HI \) — Heat index (°F)
• \( T \) — Temperature (°F)
• \( RH \) — Relative humidity (%)

Note: The equation is only valid when temperature is ≥ 80°F and relative humidity is ≥ 40%.

3. Importance of Heat Index

Details: The heat index is crucial for:

• Assessing heat-related health risks
• Planning outdoor activities
• Workplace safety regulations
• Meteorological reporting

4. Using the Calculator

Tips: Enter the temperature in °F and relative humidity in %. The calculator will only compute when T ≥ 80°F and RH ≥ 40%.

5. Frequently Asked Questions (FAQ)

Q1: Why is humidity important in heat index?
A: High humidity reduces the body's ability to cool through sweat evaporation, making the temperature feel hotter than it actually is.

Q2: What's considered a dangerous heat index?
A: Heat index above 103°F is dangerous, and above 125°F is extremely dangerous with high risk of heat stroke.

Q3: Does this work for Celsius temperatures?
A: No, this formula is specifically for Fahrenheit. For Celsius, convert to Fahrenheit first.

Q4: Why doesn't the calculator work below 80°F?
A: The formula was designed for hot conditions where humidity significantly affects perceived temperature.

Q5: How accurate is the heat index?
A: It's a good estimate but actual perception can vary based on individual factors and wind conditions.