Heat Index
Equivalent heat index vs. air temperature and relative humidity - in degrees Fahrenheit and Celsius.
The heat index can be used to indicate how an average person will perceive temperature and humidity and the human body ability to cool it self.
Heat Index in degrees Fahrenheit
The heat index in degrees Fahrenheit can be calculated as
tHI = -42.379 + 2.04901523 t + 10.14333127 φ
- 0.22475541 t φ - 0.00683783 t2 - 0.05481717 φ2
+ 0.00122874 t2 φ + 0.00085282 t φ2 - 0.00000199 (T φ)2 (1)
where
tHI = heat index (oF)
t = air temperature (oF) (t > 57oF)
φ = relative humidity (%)
Apparent Temperature Heat Stress Index (oF) | |||||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|
Relative Humidity (% RH) | Temperature (oF) | ||||||||||||
80 | 85 | 90 | 95 | 100 | 105 | 110 | 115 | 120 | 125 | 130 | 135 | 140 | |
0 | 78 | 82 | 87 | 911) | 94 | 97 | 100 | 103 | 105 | 107 | 108 | 110 | 110 |
5 | 78 | 82 | 86 | 90 | 94 | 98 | 102 | 106 | 110 | 114 | 117 | 121 | |
10 | 78 | 82 | 86 | 902) | 95 | 100 | 105 | 110 | 116 | 121 | 128 | ||
15 | 78 | 82 | 86 | 91 | 96 | 102 | 108 | 115 | 122 | 130 | |||
20 | 79 | 82 | 86 | 91 | 97 | 104 | 112 | 121 | 130 | 140 | |||
25 | 79 | 82 | 87 | 93 | 100 | 108 | 117 | 127 | 138 | ||||
30 | 79 | 83 | 88 | 94 | 102 | 112 | 122 | 134 | 148 | ||||
35 | 80 | 84 | 89 | 96 | 106 | 116 | 129 | 143 | |||||
40 | 80 | 84 | 91 | 99 | 109 | 121 | 136 | 152 | |||||
45 | 80 | 85 | 92 | 102 | 114 | 127 | 143 | ||||||
50 | 81 | 86 | 95 | 1053) | 118 | 134 | 152 | ||||||
55 | 81 | 88 | 97 | 109 | 124 | 141 | |||||||
60 | 82 | 89 | 100 | 113 | 129 | 149 | |||||||
65 | 82 | 91 | 103 | 118 | 136 | ||||||||
70 | 83 | 93 | 106 | 123 | 143 | ||||||||
75 | 84 | 95 | 109 | 1284) | |||||||||
80 | 84 | 97 | 113 | 134 | |||||||||
85 | 85 | 99 | 117 | ||||||||||
90 | 86 | 102 | 122 | ||||||||||
95 | 86 | 104 | |||||||||||
100 | 87 | 107 |
- T(oC) = 5/9[T(oF) - 32]
Sunstroke and heat exhaustion:
1) Caution - Fatigue is possible with prolonged exposure and/or physical activity
2) Extreme Caution - Sunstroke, heat cramps and heat exhaustion are possible with prolonged exposure and/or physical activity
3) Danger - Sunstroke, heat cramps and heat exhaustion are likely. Heat stroke is possible with prolonged exposure and/or physical activity
4) Extreme Danger - Heatstroke/sunstroke is highly likely with continued exposure
Heat Index in degrees Celsius
Heat index in degrees Celsius: