Why does this use knots instead of mph?

Knots are the standard unit of speed at sea. One knot equals one nautical mile per hour (roughly 1.852 km/h). The tool converts knots to km/h internally before applying the NOAA formula.

At what conditions does wind chill apply?

The NOAA wind chill index is defined for air temperatures at or below 10 °C (50 °F) and wind speeds above 3 knots (~4.8 km/h). Outside those ranges the apparent temperature equals the air temperature — the tool shows a note when this applies.

What formula is used?

The NOAA 2001 wind chill formula: WC = 13.12 + 0.6215·T − 11.37·V^0.16 + 0.3965·T·V^0.16, where T is temperature in °C and V is wind speed in km/h. This is the same formula used by Environment Canada and the US National Weather Service.

Does wind chill affect equipment or machinery?

Wind chill is a human-comfort index only. It describes how cold exposed skin feels, not the physical temperature of objects. Engine blocks, instruments, and fuel cool to the actual air temperature, not the wind chill value.

How accurate is the result?

The formula is accurate for typical marine conditions. It assumes standard exposed-skin conditions and average walking pace of 1.4 m/s. Wet skin or spray exposure can make conditions feel even colder than the displayed value.

Wind Chill Marine Calculator

Enter air temperature and wind speed in knots to find the apparent (felt) temperature for marine conditions.

Conditions

Temperature Unit

Air Temperature (°C)

Wind chill applies at or below 10 °C (50 °F)

Wind Speed (knots)

Must exceed 3 kn for wind chill to apply

Result

Apparent Temperature

—

Enter values to calculate

Air Temperature —

Wind Speed —

Wind Speed (km/h) —

Wind Chill Index —

Wind Chill Reference — Comfort Levels

Apparent Temp (°C)	Apparent Temp (°F)	Risk Level
0 to −9	32 to 15	Uncomfortable — dress in layers
−10 to −24	14 to −11	Very cold — risk of frostbite in prolonged exposure
−25 to −39	−13 to −38	Extreme — exposed skin can freeze within minutes
−40 and below	−40 and below	Danger — exposed skin freezes in under 2 minutes

Summary

Enter air temperature and wind speed in knots to find the apparent (felt) temperature for marine conditions.

How it works

Enter the air temperature in °C or °F.
Enter wind speed in knots (the standard nautical unit).
Select your preferred output unit.
The tool converts knots to km/h internally, then applies the NOAA wind chill formula.
The apparent temperature and a comfort-level label are shown instantly.
Results update in real time as you adjust inputs.

Use cases

Decide whether to wear extra layers before setting out on a passage.
Brief crew on expected felt temperatures during offshore watches.
Plan anchor watches and deck duty rotations in cold weather.
Convert NWS/NOAA wind chill forecasts from mph to a knot-based display.
Training and education for marine weather courses.
Compare conditions at different watch times during a voyage.

Frequently Asked Questions

Last updated: 2026-09-19 · Reviewed by Nham Vu