Heat Index and Wind Chill Calculator
Evaluate separately selected heat-index or wind-chill equations with explicit supported domains and temperature/speed units.
YOUR CALCULATION
Result
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Calculation steps
Work through one step at a time or reveal the complete calculation. The steps use your current inputs.
How to calculate
Follow the sourced NWS preliminary/regression humidity adjustments or its separate wind-chill equation within the stated scope.
Wind chill °F=35.74+0.6215T−35.75V^0.16+0.4275TV^0.16; heat index uses the NWS Rothfusz procedure
Worked example
At 90°F and 70% relative humidity, the regression gives heat index about 105.922°F. Separately, at 0°F and 15 mph, wind chill is about −19.398°F.
Assumptions and input details
Heat scope: actual 80–110°F, RH 10–90%, resulting index at most 140°F; lower preliminary values use the NWS averaged simple formula. Wind scope: actual −50 to 50°F and speed above 3 through 100 mph. These empirical models are not blended or applied outside scope. No forecast, hazard category, frostbite duration or individualized safe exposure is calculated. Sun, clothing and individual response are excluded.
References: NWS Weather Prediction Center: heat-index procedure · NWS: wind-chill equation, assumptions and domain
Unit definitions
Unit selection is independent of language. Each selector contains only units for its physical quantity. Calculations use defined base units internally.
Using this calculator
Can I enter my own problem?
Yes. Replace the example values with your own inputs. The result, calculation steps, tables and applicable diagrams update from those inputs. Blank or invalid values clear the result; example values are never silently substituted for missing inputs.
Are the results exact?
Results use floating-point arithmetic and displayed rounding. Read the formula, assumptions and any stated data precision before interpreting the result.
Is my input uploaded?
The calculation runs in your browser. No account, file upload or external AI service is required. Inputs are not saved between page reloads.
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