Wind Chill Chart

How cold is it outside? Simply knowing the temperature doesn't tell you enough about the conditions to enable you to dress sensibly for all winter weather. Other factors including wind speed, relative humidity and sunshine play important roles in determining how cold you feel outside. A description of the character of weather known as "coldness" was proposed about 1940 by scientists working in the Antarctic. The "wind chill index" as developed to describe the relative discomfort/danger resulting from the combination of wind and temperature.

The wind chill index describes an equivalent temperature at which the heat loss from exposed flesh would be the same if the wind were near calm. For example, a wind chill index of -5 indicates that the affects of wind and temperature on exposed flesh are the same as if the air temperature were 5 degrees below zero even though the actual temperature is much higher.

The importance of the wind chill index is as an indicator of how to dress properly for winter weather. (Wind chill does not affect your car's antifreeze protection, freezing of water pipes, etc.) In dressing for cold weather an important factor to remember is that entrapped insulating air warmed by body heat is the best protection against the cold. Consequently, wear loose-fitting, lightweight, warm clothing in several layers. Outer garments should be tightly-woven, water-repellant and hooded. Mittens snug at the wrist are better protection than fingered gloves.

If you would like to calculate the wind chill index for combinations of temperature and wind other than those given in the table above, you can use the formula:

 

WC = 91.4 - (0.474677 - 0.020425 * V + 0.303107 * SQRT(V)) * (91.4 - T)
where: WC = wind chill index
V = wind speed (mph)
T = temperature (° F)

To use the chart, find the approximate temperature on the top of the chart. Read down until you are opposite the appropriate wind speed. The number which appears at the intersection of the temperature and wind speed is the wind chill index.  Here's the 1945 Chart!

Wind
Speed
MPH		 Air Temperature
(Degrees Fahrenheit)
35 30 25 20 15 10 5 0 -5 -10 -15 -20 - 25 -30 -35 -40 -45
5 33 27 21 16 12 7 1 -6 -11 -15 -20 -26 -31 -35 -41 -47 -54
10 21 16 9 2 -2 -9 -15 -22 -27 -31 -38 -45 -52 -58 -64 -70 -77
15 16 11 1 -6 -11 -18 -25 -33 -40 -45 -51 -60 -65 -70 -78 -85 -90
20 12 3 -4 -9 -17 -24 -32 -40 -46 -52 -60 -68 -76 -81 -88 -96 -103
25 7 0 -7 -15 -22 -29 -37 -45 -52 -58 -67 -75 -83 -89 -96 -104 -112
30 5 - 2 -11 -18 - 26 -33 -41 - 49 -56 -63 - 70 -78 -87 - 94 -101 -109 - 117
35 3 - 4 -13 -20 - 27 -35 -43 - 52 -60 -67 - 72 -83 -90 - 98 -105 -113 - 123
40 1 - 4 -15 -22 - 29 -36 -45 - 54 -62 -69 - 76 -87 -94 - 101 -107 -116 - 128
45 1 - 6 -17 -24 - 31 -38 -46 - 54 -63 -70 - 78 -87 -94 - 101 -108 -118 - 128
50 0 - 7 -17 -24 - 31 -38 -47 - 56 -63 -70 - 79 -88 -96 - 103 -110 -120 - 128

Links to sites with Wind Chill Tables and Calculators:
Wind Chill Chart by 7Almanac
Wind Chill Chart with Explanation
Java Chill Factor Calculator
Wind Chill Factor Calculator by Scott Blanksteen
Athena-NASA Wind Chill Chart
NOAA Wind Chill Chart: Last revised in 1945, now revised!   Revision Announcement
NWS WC Chart
Bernard Meisner's NOAA Wind Chill Calculator
NOAA Weather Calculators
Princeton's Hypothermia Action Guide
Heat and Wind Chill Index Charts
Heat and Wind Chill Formulas
Washington Post Weather Calculators

On things Cold
National Ice Center

Heat Index Chart

In an average year only the winter's cold -- not lightning, hurricanes, tornadoes, floods, or earthquakes -- takes a greater weather-related death toll than the summer's heat and humidity. In an effort to alert you to the hazards of prolonged heat/humidity episodes, the National Weather Service devised the "heat index." The heat index (HI) is an accurate measure of how hot it really feels when the affects of humidity are added to high temperature.

The human body contains several mechanisms to maintain its internal operating temperature at 98.6° F. When threatened with above "normal" temperatures, the body will try to dissipate excesss heat by varying the rate and depth of blood circulation, by losing water through the skin and sweat glands, and, as a last resort, by panting. When weather conditions force the air temperature above 90° F and the relative humidity is high, the body is doing everything it can to maintain its normal temperature. Unfortunately, conditions can exceed the body's ability to cope with the combined affects of heat and humidity. At such times the body may sucumb to any of a number of heat disorders including sunstroke, heat cramps, heat exhaustion and heatstroke.

To use the heat index charts, find the appropriate temperature at the top of the chart. 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

 

Credits for Heat / Chill tables

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