HEAT INDEX

ENVIRONMENTAL TEMERATURE (F)
70
75
80
85
90
95
100
105
110
115
120
Relative Humidity
APPARENT TEMPERATURE* (F)
0%
64
69
73
78
83
87
91
95
99
103
107
10%
65
70
75
80
85
90
95
100
105
111
116
20%
66
72
77
82
87
93
99
105
112
120
130
30%
67
73
78
84
90
96
104
113
123
135
148
40%
68
74
79
86
93
101
110
123
137
151
50%
69
75
81
88
96
107
120
135
150
60%
70
76
82
90
100
114
132
149
70%
70
77
85
93
106
124
144
80%
71
78
86
97
113
136
90%
71
79
88
102
122
100%
72
80
91
108

Note: Exposure to full sunshine can increase Heat Index values by up to 15

Combined index of heat and humidity... what it "feels like" to the body.

Source: National Oceanic and Atmospheric Administration
APPARENT TEMPERATURE (F)
HEAT STRESS RISK WITH PHYSICAL ACTIVITY AND/OR PROLONGED EXPOSURE
90 - 105
   Heat cramps or heat exhaustion possible
105 -130
   Heat cramps or heat exhaustion likely, Heatstroke   possible
130 and up
   Heatstroke highly likely

Interactivity Redefined

This Heat Index Chart provides general guidelines for assessing the potential severity of heat stress. Individual reactions to heat will vary. It should be remembered that heat illness can occur at lower temperatures than indicated on the chart. In addition, studies indicate that susceptibility to heat illness tends to increase with age.

How To Use The Heat Index Chart:

  1. Across the top of the chart, locate the ENVIRONMENTAL TEMPERATURE, i.e., the air temperature.
  2. Down the left side of the chart, locate the RELATIVE HUMIDTY.
  3. Follow across and down to find the APPARENT TEMPERATURE. Apparent Temperature is the combined index of heat and humidity. It is an index of the body’s sensation of heat caused by the temperature and humidity (the reverse of the “wind chill factor”).
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