Heat Index Charts
Heat Index Charts
To use the heat index charts, find the appropriate temperature at the top of the chart. There are two charts on this page. Read down until you are opposite the humidity/dewpoint. The number which appears at the intersection of the temperature and humidity/dewpoint is the heat index.
Heat Index Chart (Temperature & Dewpoint)
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 |
Note: Exposure to full sunshine can increase HI values by up to 15° F |
Heat Index Chart (Temperature & Relative Humidity)
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 |
Note: Exposure to full sunshine can increase HI values by up to 15° F |
For the more ambitious who would like to calculate the heat index,
here is the formula:
![Formula for finding heat index](/graphics/heatdx.gif)
where:
HI = Heat Index
T = Temperature (° F)
RH = Relative Humidity (%)
Source: Meteorology for Scientists and Engineers, 2nd edition by Roland B. Stull
Better yet, input any temperature above 80 ° Fahrenheit along with
a relative humidity.