# Heat Index Calculators And Tables

This calculator requires the use of Javascript enabled and capable browsers. This script calculates the Heat Index ( or "feels like" temperature) from the relative humidity or from the dew point, along with the ambient air temperature in degrees Fahrenheit (F). In either calculator, enter the temperature in degrees (F) and the other factors (numerical entry only); then click on Calculate. The calculator will return the Heat Index and other relative information. You may independently clear the values of either calculator to start over. The heat Index does not really occur below 85 degrees F. You should also know that possible increases of up to 15 degrees F are possible in full, open sunlight for more than an hour. We have also provided tables below the calculators for those that don't feel like entering data and clicking the mouse. If you are confused by Fahrenheit and Celsius, there is a converter as a part of the calculator. Enter data in either field and click anywhere in the calculator for the result to appear. (Whew... with that behind us, the heat is OFF!) For those of you that are capable of mental math with a pencil and are up to a challenge, try this by hand. If you would like to make a manual calculation of the Heat Index, here is the formula:

The formula variables are: HI = Heat Index, T = Temperature (°F), RH = Relative Humidity (%)

Temperature Converter (If needed)
°C  °F

## Heat Index Calculator ( From Relative Humidty )

Degrees Fahrenheit (°F): Relative Humidity:

Calculated Results
Heat Index (HI) - "Feels like":
Dewpoint (°F): =

## Heat Index Calculator ( From Dew Point )

Degrees Fahrenheit (°F): Dewpoint (°F):

Calculated Results
Heat Index:Relative Humidity =

## Heat Index Tables

In the heat index tables below, find the appropriate temperature at the top of the table. The humidity table is immediately below this and the dewpoint table is below it. The number which appears at the intersection of the temperature and either the humidity on the left or the dewpoint on the left, is the heat index.
 RH(%) Temperature (°F) 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 90 119 123 128 132 137 141 146 152 157 163 168 174 180 186 193 199 85 115 119 123 127 132 136 141 145 150 155 161 166 172 178 184 190 80 112 115 119 123 127 131 135 140 144 149 154 159 164 169 175 180 75 109 112 115 119 122 126 130 134 138 143 147 152 156 161 166 171 70 106 109 112 115 118 122 125 129 133 137 141 145 149 154 158 163 65 103 106 108 111 114 117 121 124 127 131 135 139 143 147 151 155 60 100 103 105 108 111 114 116 120 123 126 129 133 136 140 144 148 55 98 100 103 105 107 110 113 115 118 121 124 127 131 134 137 141 50 96 98 100 102 104 107 109 112 114 117 119 122 125 128 131 135 45 94 96 98 100 102 104 106 108 110 113 115 118 120 123 126 129 40 92 94 96 97 99 101 103 105 107 109 111 113 116 118 121 123 35 91 92 94 95 97 98 100 102 104 106 107 109 112 114 116 118 30 89 90 92 93 95 96 98 99 101 102 104 106 108 110 112 114

 Dewpoint(°F) Temperature (°F) 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 65 94 95 96 97 98 100 101 102 103 104 106 107 108 109 110 112 66 94 95 97 98 99 100 101 103 104 105 106 108 109 110 111 112 67 95 96 97 98 100 101 102 103 105 106 107 108 110 111 112 113 68 95 97 98 99 100 102 103 104 105 107 108 109 110 112 113 114 69 96 97 99 100 101 103 104 105 106 108 109 110 111 113 114 115 70 97 98 99 101 102 103 105 106 107 109 110 111 112 114 115 116 71 98 99 100 102 103 104 106 107 108 109 111 112 113 115 116 117 72 98 100 101 103 104 105 107 108 109 111 112 113 114 116 117 118 73 99 101 102 103 105 106 108 109 110 112 113 114 116 117 118 119 74 100 102 103 104 106 107 109 110 111 113 114 115 117 118 119 121 75 101 103 104 106 107 108 110 111 113 114 115 117 118 119 121 122 76 102 104 105 107 108 110 111 112 114 115 117 118 119 121 122 123 77 103 105 106 108 109 111 112 114 115 117 118 119 121 122 124 125 78 105 106 108 109 111 112 114 115 117 118 119 121 122 124 125 126 79 106 107 109 111 112 114 115 117 118 120 121 122 124 125 127 128 80 107 109 110 112 114 115 117 118 120 121 123 124 126 127 128 130 81 109 110 112 114 115 117 118 120 121 123 124 126 127 129 130 132 82 110 112 114 115 117 118 120 122 123 125 126 128 129 131 132 133
Updated: 7/26/11
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