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Wind Chill Index

Effective Temperature of air in movement.

The convective heat loss due to wind can be dramatic. In the table below the wind chill effect is illustrated for air speeds up to 10 m/s (36 km/h, 2000 ft/min, 22 mph), or "fresh breeze" according the Beaufort wind scale.

Wind Chill Effect
Air SpeedChill Effect
(m/s)(ft/min)(oC)(oF)
0.1 20 0 0
0.25 50 0.5 2
1.5 300 4 7
3 600 6 10.5
5 1000 7 13
8 1575 8 15
10 2000 9 16

Wind Chill Index - Wind Speed in km/h and Temperature in degrees Celsius

"Chilled" air temperature can be expressed as a function of wind speed and ambient air temperature

twC = 13.12 + 0.6215 ta - 11.37 v0.16 + 0.3965 ta v0.16                        (1)

where

twC = effective "wind" temperature (oC)

ta = air temperature (oC)

v = wind speed (km/h)

Wind Chill Index -  SI Units
"Chilled" Air Temperature (oC)
Ambient Air Temperature (oC)Wind Speed (km/h)
510152030405060
10 10 9 8 7 7 6 5 5
5 4 3 2 1 0 -1 -1 -2
0 -2 -3 -4 -5 -6 -7 -8 -9
-5 -7 -9 -11 -12 -13 -14 -15 -16
-10 -13 -15 -17 -18 -20 -21 -22 -23
-15 -19 -21 -23 -24 -26 -27 -29 -30
-20 -24 -27 -29 -30 -33 -34 -35 -36
-25 -30 -33 -35 -37 -39 -41 -42 -43
-30 -36 -39 -41 -43 -46 -48 -49 -50
-35 -41 -45 -48 -49 -52 -54 -56 -57
-40 -47 -51 -54 -56 -59 -61 -63 -64
  • 1 km/h = 0.2778 m/s = 54.68 ft/min = 0.6214 mph = 0.5396 knot

Wind Chill Index - Effective Temperature - effect of wind velocity on temperature diagram - km/h and celcius

Download and print Wind Chill Index chart

Wind Chill Index - Wind Speed in mph and Temperature in degrees Fahrenheit

The "Chilled" air temperature can also be expressed as a function of wind velocity and ambient air temperature as

twF = 35.74 + 0.6215 ta - 35.75 v0.16 + 0.4275 ta v0.16                        (2)

where

twF = effective temperature (oF)

ta = air temperature (oF)

v = wind speed (mph)

Wind Chill Index - Imperial Units
"Chilled" Air Temperature (oF)
Ambient Air Temperature (oF)Wind Speed (mph)
510152025303540
40 36 34 32 30 29 28 28 27
35 31 27 25 24 23 21 21 20
30 25 21 19 17 16 14 14 13
25 19 15 13 11 9 7 7 6
20 13 9 6 4 3 0 0 -1
15 7 3 0 -2 -4 -7 -7 -8
10 1 -4 -7 -9 -11 -14 -14 -15
5 -5 -10 -13 -15 -17 -21 -21 -22
0 -11 -16 -19 -22 -24 -27 -27 -29
-5 -16 -22 -26 -29 -31 -37 -34 -36
-10 -22 -28 -32 -35 -37 -41 -41 -43
-15 -28 -35 -39 -42 -44 -48 -48 -50
-20 -34 -41 -45 -48 -51 -55 -55 -57
-25 -40 -47 -51 -55 -58 -62 -62 -64
-30 -46 -53 -58 -61 -64 -69 -69 -71
-35 -52 -59 -64 -68 -71 -76 -76 -78
-40 -57 -66 -71 -74 -78 -82 -82 -84

Wind Chill Index - Effective Temperature - effect of wind velocity on temperature diagram - mph degrees fahrenheit

Download and print Wind Chill Index chart

Wind Chill Effects
Wind ChillPossible Effects
30 oF or higher Generally unpleasant
30o to 15 oF Unpleasant
14o to 0 oF Very unpleasant
-1o to -20 oF Frostbite possible
-21o to -60 oF Frostbite likely - outdoor activities dangerous
-61o or lower Exposed flesh freezes within 30 seconds
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