Wind Chill Calculator — Free Online Wind Chill Index Tool

How to Use the Wind Chill Calculator

1. Enter the air temperature: Type the current outdoor air temperature in degrees Fahrenheit into the Temperature field. You can find this reading from your local weather service, a personal weather station, or an outdoor thermometer. The NWS wind chill formula is designed for temperatures at or below 50°F, so the calculator works best in cold weather conditions where wind chill is a meaningful safety metric.
2. Enter the wind speed: Input the current wind speed in miles per hour. You can find sustained wind speeds from your local weather report, a weather app, or a personal anemometer. The formula requires a minimum wind speed of 3 mph because at lower speeds, wind has negligible impact on perceived temperature. Use the sustained wind speed rather than gust speed for the most representative wind chill calculation.
3. Review the wind chill temperature: The calculator instantly displays the wind chill in both Fahrenheit and Celsius, along with a qualitative descriptor like Cool, Cold, Very Cold, or Extreme Cold. This tells you how the conditions will actually feel on any exposed skin when you step outdoors.
4. Check frostbite risk and timing: The results panel shows the current frostbite risk level and the estimated time before frostbite can develop on exposed skin. Use this information to decide whether you need full face and hand coverage, and how long you can safely remain outdoors before seeking shelter to warm up.

All results update in real time as you change either value. Adjust the wind speed to see how gusts versus sustained winds change the wind chill, or lower the temperature to simulate overnight conditions and plan your morning routine accordingly.

Wind Chill Formula

Variables Explained

• T (Temperature): The ambient air temperature in degrees Fahrenheit, measured by a thermometer in a shaded, ventilated location. This is the standard temperature reading you get from weather reports. The formula is valid for temperatures at or below 50°F, as wind chill becomes meaningless at warmer temperatures where there is no risk of cold injury.
• V (Wind Speed): The sustained wind speed in miles per hour at an average height of 5 feet, which represents the typical face level of a walking adult. Weather stations measure wind at 33 feet, and the NWS formula includes a built-in adjustment to estimate the wind at face level. The minimum valid wind speed is 3 mph.
• Wind Chill Index: The resulting value represents the equivalent temperature in still air that would produce the same rate of heat loss from exposed skin as the actual combination of temperature and wind. It is always equal to or lower than the actual air temperature when wind is present.
• V^0.16: This exponent represents the nonlinear relationship between wind speed and the rate of convective heat loss. Doubling the wind speed does not double the heat loss; rather, the relationship follows a power law where the effect of each additional mph of wind diminishes at higher speeds.

Step-by-Step Example

Suppose the air temperature is 10°F and the wind is blowing at 25 mph:

1. Start with the constant: 35.74
2. Add 0.6215 x 10 = 6.215 → running total: 41.955
3. Calculate 25^0.16 = 1.738
4. Subtract 35.75 x 1.738 = 62.133 → running total: -20.178
5. Add 0.4275 x 10 x 1.738 = 7.430 → running total: -12.748
6. Wind chill = -12.7°F (approximately -24.9°C)

At 10°F with 25 mph winds, the wind chill is approximately minus 13°F. This falls in the frostbite risk zone where exposed skin can develop frostbite in 10 to 30 minutes, making face and hand protection essential for any outdoor activity.

Practical Examples

Example 1: David's Morning Run

David is an avid runner in Minneapolis who runs outdoors year-round. On a January morning, the temperature is 15°F with 20 mph winds. He uses the wind chill calculator before heading out:

• Temperature: 15°F
• Wind speed: 20 mph
• Wind chill result: approximately -2°F (-19°C)
• Frostbite risk: Low (frostbite possible after 30+ minutes)

David plans a 35-minute run, so he wears a moisture-wicking base layer, a windproof running jacket, insulated gloves, a balaclava covering his face, and thermal running tights. He keeps his run under 30 minutes of full exposure and warms up immediately afterward. The wind chill calculation helps him avoid underestimating the conditions.

Example 2: Angela's School Bus Wait

Angela is a parent in Buffalo, New York, where her children wait for the school bus each morning. The forecast shows 5°F with sustained winds of 30 mph. She checks the wind chill to decide whether to drive them to school instead:

• Temperature: 5°F
• Wind speed: 30 mph
• Wind chill result: approximately -19°F (-28°C)
• Frostbite risk: Moderate (frostbite in 10 to 30 minutes)

With a wind chill of minus 19°F and frostbite possible in 10 to 30 minutes, Angela decides to drive her children to school rather than having them wait at the bus stop for 15 minutes. The calculator helps parents make informed decisions about child safety during cold snaps.

Example 3: Brian's Ski Trip Planning

Brian is planning a ski trip to Colorado where the summit temperature is expected to be -5°F with wind gusts reaching 40 mph. He calculates the wind chill for the exposed summit runs:

• Temperature: -5°F
• Wind speed: 40 mph
• Wind chill result: approximately -38°F (-39°C)
• Frostbite risk: High (frostbite in 5 to 10 minutes)

At a wind chill of minus 38°F, Brian knows every inch of skin must be covered. He packs a full face balaclava, ski goggles, insulated ski gloves with liners, and plans to take warm-up breaks in the lodge every 30 to 45 minutes. He also sets a strict rule that his group moves indoors if conditions worsen beyond the forecast.

Example 4: Karen's Livestock Safety Check

Karen runs a cattle ranch in Montana. A winter storm is approaching with temperatures dropping to -10°F and winds of 35 mph. She calculates the wind chill to assess livestock safety:

• Temperature: -10°F
• Wind speed: 35 mph
• Wind chill result: approximately -41°F (-41°C)
• Frostbite risk: High (frostbite in 5 to 10 minutes on humans)

Karen moves her cattle to a windbreak shelter and ensures access to heated water troughs. While cattle tolerate cold better than humans, wind chill below minus 30°F can cause frostbite on their ears and tails. She also adjusts feed rations upward by 20% because cattle burn more calories maintaining body temperature in extreme wind chill conditions.

Wind Chill Reference Table

Values are approximate wind chill temperatures in °F based on the NWS wind chill formula.

Tips and Complete Guide

Understanding Frostbite Risk Levels

Frostbite occurs when skin tissue freezes due to prolonged exposure to cold and wind. The risk depends directly on the wind chill temperature and the duration of exposure. At wind chill values above 0°F, frostbite is unlikely for most people during normal outdoor activities. Between 0°F and minus 18°F, frostbite becomes possible after 30 minutes of continuous exposure on bare skin. Between minus 18°F and minus 32°F, frostbite can occur in 10 to 30 minutes, making gloves, hats, and face coverings essential. Below minus 32°F, frostbite risk becomes high, and any exposed skin is in danger within 5 to 10 minutes. At wind chills below minus 48°F, skin can freeze in under 5 minutes, and outdoor exposure should be limited to absolute emergencies.

Protecting Yourself and Your Family

The most effective protection against wind chill is reducing exposed skin. Wear windproof outer layers that block air movement across your body. Pay special attention to extremities because fingers, toes, ears, and the nose lose heat fastest and are the first sites of frostbite. Children and older adults are more vulnerable to cold-related injuries because they lose body heat faster than healthy adults. Never let children play outside in wind chill conditions below minus 15°F without full skin coverage and regular warm-up breaks. Pets are also at risk from wind chill, and short-haired breeds should wear dog coats during walks when the wind chill drops below 20°F.

Wind Chill and Outdoor Sports

Athletes who train and compete outdoors in winter must take wind chill seriously. Runners, cyclists, skiers, and football players all face significant wind chill exposure. Cycling creates its own wind chill because forward speed adds to the ambient wind. A cyclist riding at 15 mph on a 20°F day with 5 mph headwind effectively experiences 20 mph of wind, pushing the wind chill down to about 4°F. Similarly, downhill skiers can reach speeds of 30 to 60 mph, creating extreme wind chill on exposed faces even on relatively mild mountain days. Always check the wind chill before outdoor training sessions and adjust your clothing layers and exposure time accordingly. Our heat index calculator is the warm-weather counterpart for summer training safety.

Common Mistakes to Avoid

• Ignoring wind speed in cold weather: A calm 10°F day feels dramatically different from a 10°F day with 25 mph winds (wind chill around minus 9°F). Always check the wind chill, not just the temperature, before going outside in winter.
• Wearing cotton in cold and windy conditions: Cotton absorbs moisture and loses all insulating ability when wet. In wind chill conditions, wet cotton against your skin accelerates heat loss dangerously. Use synthetic or wool base layers that wick moisture away from the body.
• Assuming wind chill applies to objects: Many people believe their car engine or house pipes will freeze faster based on wind chill temperature. Wind chill only affects warm-blooded organisms. Pipes freeze based on actual air temperature, though wind does speed up the cooling process to reach that temperature.
• Underestimating cumulative exposure: Short trips between heated buildings and cars can add up. Ten 3-minute exposures to a minus 20°F wind chill during a day of errands accumulates 30 minutes of exposure and can cause frostbite symptoms on fingers and ears.
• Not accounting for altitude: Mountain environments combine low temperatures with higher wind speeds. A summit that reads 25°F at the base station may be 10°F at the peak with 40 mph gusts, creating a wind chill of minus 25°F.

Frequently Asked Questions