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Wind Chill & Heat Index Calculator

See how cold or hot it really feels using official National Weather Service formulas. Check wind chill danger, frostbite risk, heat index, and heat illness categories in one tool.

Wind chill estimates how cold it feels on exposed skin when air temperature and wind combine.

Feels Like

21.6°F

-5.8°C

Danger Level

Caution

Frostbite is unlikely, but prolonged exposure can still be uncomfortable.

Formula note

Calculated with the official NWS wind chill formula.

Editorial noteMaintained by EveryCalc - Reviewed June 2026

EveryCalc calculators are designed for fast, practical estimates with transparent inputs and no required account. We use plain formulas, visible assumptions, and related tools so visitors can check the result from more than one angle.

Results are informational only. For financial, tax, legal, medical, construction, or other high-impact decisions, verify the output against primary sources or a qualified professional.

Learn more about our review process on the EveryCalc methodology page.

How this calculator works

What this page estimates

This Wind Chill & Heat Index Calculator is built to give a quick, browser-based estimate for wind chill & heat index. See how cold or hot it really feels using official National Weather Service formulas. Check wind chill danger, frostbite risk, heat index, and heat illness categories in one tool. The inputs stay on the page during normal use, and the result should be treated as an estimate for planning, comparison, or education rather than professional advice.

Calculation approach

The calculator applies the standard relationship implied by the inputs, then formats the answer so it can be checked and reused. For health tools, the most important step is using consistent units, rates, time periods, and assumptions before comparing the result with another calculator or outside quote.

Example workflow

For example, start with a realistic value you already know, change one input at a time, and watch how the answer moves. That makes it easier to tell whether the result is being driven by the main amount, the rate, the time period, or a unit conversion.

Practical checks

  • Use current, real-world numbers when the result affects money, health, tax, or legal decisions.
  • Run a low, base, and high case when the inputs are estimates.
  • Check the related calculators below when the next decision depends on a different assumption.

How to interpret the wind chill & heat index result

Best use

Use the result as an informational wellness estimate that can help organize measurements, targets, or timing before a conversation with a clinician.

Cross-check

Compare the output with your own records, device readings, lab values, medication instructions, or guidance from a qualified health professional.

Watch for

Do not use this page to diagnose, treat, or ignore symptoms. Health calculators are most useful when they make questions clearer, not when they replace care.

This page belongs to the Health calculator library, so the answer should be read in the context of the decision you are modeling rather than as a universal rule.

Before relying on this wind chill & heat index estimate

Most calculator mistakes come from the inputs, not the arithmetic. Use this short audit before you reuse the answer in a spreadsheet, quote, application, or important conversation.

Use current measurements

Recent weight, height, age, activity, nutrition, sleep, or timing inputs matter more than remembered estimates.

Look for context

A calculator can organize a wellness number, but it cannot read symptoms, medical history, medications, or lab results.

Escalate high-impact questions

Use clinical guidance for pregnancy, dosage, heart, risk, illness, or treatment decisions.

Rerun this page when measurements change, a clinician gives new guidance, or the result is being used for a new goal.

How to Use

  1. Choose the Wind Chill or Heat Index tab.
  2. Enter the air temperature and pick Fahrenheit or Celsius.
  3. For wind chill, enter wind speed in mph or km/h. For heat index, enter relative humidity.
  4. Review the feels-like temperature, danger category, and the safety guidance shown below the result.

Frequently Asked Questions

When is the wind chill formula accurate?

The official NWS wind chill formula is intended for temperatures at or below 50°F and wind speeds above 3 mph. Outside that range, this calculator shows the air temperature and explains that the formula is not officially applicable.

What is heat index?

Heat index is the apparent temperature your body experiences when heat and humidity are combined. Higher humidity slows sweat evaporation, making the air feel hotter than the thermometer reading.

Why can wind chill be lower than the actual temperature?

Moving air removes heat from exposed skin more quickly than still air. That extra heat loss makes conditions feel colder and increases the risk of cold-related injuries like frostbite.

What heat index level is dangerous?

According to standard NWS guidance, heat index values from 90°F to 103°F are extreme caution, 103°F to 124°F are danger, and 125°F or higher are extreme danger. Risk rises further with sun exposure, exertion, age, and dehydration.

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