Detailed Wind Chill Factor, Heat Index, Dew Point Calculation
Wind-Chill, Heat Index, Dew Point Calculator
An online meteorological calculator helps you to determine the wind chill factor, heat index and dew points value.
| Temp. (°F) | Wind Speed (mph) | ||||||||
|---|---|---|---|---|---|---|---|---|---|
| 5 | 10 | 15 | 20 | 25 | 30 | 35 | 40 | 45 | |
| 40 | 36 | 34 | 32 | 30 | 29 | 28 | 28 | 27 | 26 |
| 35 | 31 | 27 | 25 | 24 | 23 | 22 | 21 | 20 | 19 |
| 30 | 25 | 21 | 19 | 17 | 16 | 15 | 14 | 13 | 12 |
| 25 | 19 | 15 | 13 | 11 | 9 | 8 | 7 | 6 | 5 |
| 20 | 13 | 9 | 6 | 4 | 3 | 1 | 0 | -1 | -2 |
| 15 | 7 | 3 | 0 | -2 | -4 | -5 | -7 | -8 | -9 |
| 10 | 1 | -4 | -7 | -9 | -11 | -12 | -14 | -15 | -16 |
| 5 | -5 | -10 | -13 | -15 | -17 | -19 | -21 | -22 | -23 |
| 0 | -11 | -16 | -19 | -22 | -24 | -26 | -27 | -29 | -30 |
| -5 | -16 | -22 | -26 | -29 | -31 | -33 | -34 | -36 | -37 |
| -10 | -22 | -28 | -32 | -35 | -37 | -39 | -41 | -43 | -44 |
| -15 | -28 | -35 | -39 | -42 | -44 | -46 | -48 | -50 | -51 |
| -20 | -34 | -41 | -45 | -48 | -51 | -53 | -55 | -57 | -58 |
| -25 | -40 | -47 | -51 | -55 | -58 | -60 | -62 | -64 | -65 |
| -30 | -46 | -53 | -58 | -61 | -64 | -67 | -69 | -71 | -72 |
| -35 | -52 | -59 | -64 | -68 | -71 | -73 | -76 | -78 | -79 |
| -40 | -57 | -66 | -71 | -74 | -78 | -80 | -82 | -84 | -86 |
| -45 | -63 | -72 | -77 | -81 | -84 | -87 | -89 | -91 | -93 |
| Frostbite Times | 5 minutes | 10 minutes | 30 minutes |
| Temp. (°F) | Relative Humidity (%) | ||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 40 | 45 | 50 | 55 | 60 | 65 | 70 | 75 | 80 | 85 | 90 | 95 | 100 | |
| 110 | 136 | 143 | 152 | 161 | 171 | 182 | 194 | 206 | 219 | 233 | 247 | 262 | 278 |
| 108 | 130 | 137 | 144 | 153 | 162 | 172 | 182 | 193 | 205 | 218 | 231 | 245 | 260 |
| 106 | 124 | 130 | 137 | 145 | 153 | 162 | 172 | 182 | 193 | 204 | 216 | 229 | 243 |
| 104 | 119 | 124 | 131 | 137 | 145 | 153 | 161 | 171 | 181 | 191 | 202 | 214 | 226 |
| 102 | 114 | 119 | 124 | 130 | 137 | 144 | 152 | 160 | 169 | 179 | 189 | 199 | 210 |
| 100 | 109 | 114 | 118 | 124 | 129 | 136 | 143 | 150 | 158 | 167 | 176 | 185 | 195 |
| 98 | 105 | 109 | 113 | 117 | 123 | 128 | 134 | 141 | 148 | 156 | 164 | 172 | 181 |
| 96 | 101 | 104 | 108 | 112 | 116 | 121 | 126 | 132 | 138 | 145 | 152 | 160 | 168 |
| 94 | 97 | 100 | 102 | 106 | 110 | 114 | 119 | 124 | 129 | 135 | 141 | 148 | 155 |
| 92 | 94 | 96 | 99 | 101 | 105 | 108 | 112 | 116 | 121 | 126 | 131 | 137 | 143 |
| 90 | 91 | 93 | 95 | 97 | 100 | 103 | 106 | 109 | 113 | 117 | 122 | 127 | 132 |
| 88 | 88 | 89 | 91 | 93 | 95 | 98 | 100 | 103 | 106 | 110 | 113 | 117 | 121 |
| 86 | 85 | 87 | 88 | 89 | 91 | 93 | 95 | 97 | 100 | 102 | 105 | 108 | 112 |
| 84 | 83 | 84 | 85 | 86 | 88 | 89 | 90 | 92 | 94 | 96 | 98 | 100 | 103 |
| 82 | 81 | 82 | 83 | 84 | 84 | 85 | 86 | 88 | 89 | 90 | 91 | 93 | 95 |
| 80 | 80 | 80 | 81 | 81 | 82 | 82 | 83 | 84 | 84 | 85 | 86 | 86 | 87 |
| Classification: | Very Warm | Hot | Very Hot | Extremely Hot |
| Temp. (°F) | Relative Humidity (%) | ||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 40 | 45 | 50 | 55 | 60 | 65 | 70 | 75 | 80 | 85 | 90 | 95 | 100 | |
| 100 | 71.3 | 74.8 | 78 | 80.9 | 83.6 | 86.1 | 88.4 | 90.6 | 92.7 | 94.7 | 96.5 | 98.3 | 100 |
| 99 | 70.4 | 73.9 | 77.1 | 80 | 82.7 | 85.1 | 87.5 | 89.7 | 91.7 | 93.7 | 95.5 | 97.3 | 99 |
| 97 | 68.6 | 72.1 | 75.2 | 78.1 | 80.8 | 83.3 | 85.6 | 87.7 | 89.8 | 91.7 | 93.6 | 95.3 | 97 |
| 95 | 66.9 | 70.3 | 73.4 | 76.3 | 78.9 | 81.4 | 83.7 | 85.8 | 87.8 | 89.8 | 91.6 | 93.3 | 95 |
| 93 | 65.1 | 68.5 | 71.6 | 74.4 | 77 | 79.5 | 81.7 | 83.9 | 85.9 | 87.8 | 89.6 | 91.3 | 93 |
| 91 | 63.3 | 66.7 | 69.8 | 72.6 | 75.2 | 77.6 | 79.8 | 82 | 84 | 85.8 | 87.6 | 89.4 | 91 |
| 90 | 62.4 | 65.8 | 68.8 | 71.6 | 74.2 | 76.6 | 78.9 | 81 | 83 | 84.9 | 86.7 | 88.4 | 90 |
| 88 | 60.6 | 64 | 67 | 69.8 | 72.4 | 74.7 | 77 | 79.1 | 81 | 82.9 | 84.7 | 86.4 | 88 |
| 86 | 58.9 | 62.2 | 65.2 | 67.9 | 70.5 | 72.9 | 75.1 | 77.1 | 79.1 | 81 | 82.7 | 84.4 | 86 |
| 84 | 57.1 | 60.4 | 63.4 | 66.1 | 68.6 | 71 | 73.2 | 75.2 | 77.2 | 79 | 80.7 | 82.4 | 84 |
| 82 | 55.3 | 58.6 | 61.5 | 64.2 | 66.7 | 69.1 | 71.2 | 73.3 | 75.2 | 77 | 78.8 | 80.4 | 82 |
| 81 | 54.4 | 57.7 | 60.6 | 63.3 | 65.8 | 68.1 | 70.3 | 72.3 | 74.2 | 76.1 | 77.8 | 79.4 | 81 |
| 79 | 52.6 | 55.9 | 58.8 | 61.5 | 63.9 | 66.2 | 68.4 | 70.4 | 72.3 | 74.1 | 75.8 | 77.4 | 79 |
| 77 | 50.8 | 54 | 56.9 | 59.6 | 62.1 | 64.3 | 66.5 | 68.5 | 70.4 | 72.1 | 73.8 | 75.5 | 77 |
| 75 | 49.1 | 52.2 | 55.1 | 57.7 | 60.2 | 62.4 | 64.6 | 66.5 | 68.4 | 70.2 | 71.9 | 73.5 | 75 |
| 74 | 48.2 | 51.3 | 54.2 | 56.8 | 59.2 | 61.5 | 63.6 | 65.6 | 67.4 | 69.2 | 70.9 | 72.5 | 74 |
| 72 | 46.4 | 49.5 | 52.4 | 55 | 57.4 | 59.6 | 61.7 | 63.6 | 65.5 | 67.2 | 68.9 | 70.5 | 72 |
| 70 | 44.6 | 47.7 | 50.5 | 53.1 | 55.5 | 57.7 | 59.8 | 61.7 | 63.5 | 65.3 | 66.9 | 68.5 | 70 |
| 68 | 42.8 | 45.9 | 48.7 | 51.2 | 53.6 | 55.8 | 57.9 | 59.8 | 61.6 | 63.3 | 65 | 66.5 | 68 |
| 66 | 41 | 44.1 | 46.8 | 49.4 | 51.7 | 53.9 | 55.9 | 57.9 | 59.7 | 61.4 | 63 | 64.5 | 66 |
| 64 | 39.2 | 42.3 | 45 | 47.5 | 49.9 | 52 | 54 | 55.9 | 57.7 | 59.4 | 61 | 62.5 | 64 |
| 63 | 38.3 | 41.4 | 44.1 | 46.6 | 48.9 | 51.1 | 53.1 | 55 | 56.7 | 58.4 | 60 | 61.5 | 63 |
| 61 | 36.5 | 39.5 | 42.3 | 44.7 | 47 | 49.2 | 51.2 | 53 | 54.8 | 56.5 | 58 | 59.6 | 61 |
| 59 | 34.7 | 37.7 | 40.4 | 42.9 | 45.2 | 47.3 | 49.2 | 51.1 | 52.8 | 54.5 | 56.1 | 57.6 | 59 |
| 57 | 33 | 35.9 | 38.6 | 41 | 43.3 | 45.4 | 47.3 | 49.2 | 50.9 | 52.5 | 54.1 | 55.6 | 57 |
| Very Uncomfortable | Uncomfortable | OK for most | Comfortable | Dry |
The following formulas to calculate the wind chill factor
WC (Wind Chill, °F) = 35.74 + 0.6215 × T - 35.75 × V 0.16 + 0.4275 × T × V 0.16
Where:
V is the wind speed in miles per hour (mph),
T is the air temperature in Fahrenheit (°F).
Wind (mph) = 0.621371 × Wind (km/h)
Wind (mph) = 2.23694 × Wind (m/s)
Wind (mph) = 0.681818 × Wind (ft/s)
Wind (mph) = 1.15077945 × Wind (kts)
Where,
Wind (mph) is the wind speed in miles per hour,
Wind (km/h) is the wind speed in kilometers per hour,
Wind (m/s) is the wind speed in meters per second,
Wind (ft/s) is the wind speed in feet per second,
Wind (kts) is the wind speed in knots.
TF = 1.8 × TC + 32
TF = 1.8 × (TK - 273.15) + 32
TC = 0.55556 × (TF - 32)
TK = ( 0.55556 × (TF - 32) ) + 273.15
Where,
TF is temperature in Fahrenheit,
TC is temperature in Celsius,
TK is temperature in Kelvin.
The following basic formula to calculate the heat index
HI (Heat Index, °F) = C1 + C2 T + C3 RH + C4 T RH + C5 T2 + C6 RH2 + C7 T2 RH + C8 T RH2 + C9 T2 RH2 + CF
Where:
HI is the heat index (°F),
T is the air temperature in Fahrenheit (°F),
RH is the relative humidity (%),
CF is the correction factor,
C1 = -42.379,
C2 = 2.04901523,
C3 = 10.14333127,
C4 = -0.22475541,
C5 = -6.83783 × 10 -3,
C6 = -5.481717 × 10 -2,
C7 = 1.22874 × 10 -3,
C8 = 8.5282 × 10 -4,
C9 = -1.99 × 10 -6.
If 80°F ≤ T ≤ 112°F, RH ≤ 13%; CF (Correction Factor) = - ([13 - RH] / 4) × ([17 - |T - 95|] / 17)0.5
If 80°F ≤ T ≤ 87°F, RH > 85%; CF (Correction Factor) = 0.02 × (RH - 85) × (87 - T)
The following basic formula to calculate the Dew point
Tdew = (237.3 × [ln(RH/100) + ( (17.27×T) / (237.3+T) )]) / (17.27 - [ln(RH/100) + ( (17.27×T) / (237.3+T) )])
Where,
Tdew is dew point temperature in degrees Celsius (°C)
T is air temperature in degrees Celsius (°C)
RH is relative humidity (%)
ln is natural logarithm
The dew point is the temperature to which air must be cooled to become saturated with water vapor.
When cold weather threatens, follow these tips for survival.
Stay dry. Wet clothing results in much faster heat loss from your body. Wear waterproof insulated boots.
Stay covered. Wear mittens or gloves, and wear a hat. At least half of your body heat is lost if your head is not covered.
Dress layered. Trapped air between loose fitting clothing helps to insulate.
When extreme heat threatens, follow these tips for survival.
Find air conditioning.
Avoid strenuous activities.
Watch for heat illness.
Wear light clothing.
Check on family members and neighbors.
Drink plenty of fluids.
Watch for heat cramps, heat exhaustion, and heat stroke.
Never leave people or pets in a closed car.
Frostbite has historically been described in terms of degrees of frostbite, similar to that of burns:
First degree frostbite:
This is the 1st degree of frostbite also known as frost nip. This form of frostbite may appear as white, waxy, cold skin.
After rewarming the affected area with warm water the frostbitten area may turn red and peel like a sunburn.
Second degree frostbite:
This is the 2nd degree of frostbite that may be numb and feel hard to the touch. Your skin may even stay indented after being poked.
Third degree frostbite:
This is the 3rd degree of frostbite and considered the most severe case. Your skin tissue may appear white and frozen solid, but will later die and turn black.
When temperature at 27-32°C or 80-90°F
Caution: fatigue is possible with prolonged exposure and activity. Continuing activity could result in heat cramps.
When temperature at 32-41°C or 90-105°F
Extreme caution: heat cramps and heat exhaustion are possible. Continuing activity could result in heat stroke.
When temperature at 41-54°C or 105-130°F
Danger: heat cramps and heat exhaustion are likely; heat stroke is probable with continued activity.
When temperature Over 54°C
Over 130°F
People accustomed to temperate climates often begin to feel uncomfortable when the dew point gets above 15 °C (59 °F)
| Dew point | Relative humidity at 32°C (90°F) | |
|---|---|---|
| Over 26°C | Over 80°F | 73% and higher |
| 24 - 26°C | 75-80°F | 62-72% |
| 21-24°C | 70-74°F | 52-61% |
| 18-21°C | 65-69°F | 44-51% |
| 16 - 18°C | 60-64°F | 37-43% |
| 13 - 16°C | 55-59°F | 31-36% |
| 10-12°C | 50-54°F | 26-30% |
| Under 10°C | Under 50°F | 25% and lower |