Heat Index Chart

The Heat Index is a combination of the current outdoor temperature and the relative humidity, or amount of moisture in the air. The higher the outdoor temperature and relative humidity, the greater the heat index and more at risk you and your pets are to suffer from heat problems.

If the Heat Index value is about 105 degrees, the National Weather Service will issue a heat advisory, and special precautions are necessary.

Heat Index Chart
Temperature and Relative Humidty



TEMPERATURE 

RH(%)	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	159	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	137	131	135	140	144	149	154	159	164	169	175	180
75	109	112	115	118	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 Heat Index Values by up to 15%.
Strong, dry winds are also very dangerous.

Heat Index Values greater than 90 are considered Extreme
Heat Index Values greater than 100 are considered Hazardous
Heat Index Values greater than 110 are considered Dangerous

Chart courtesy http://www.ncdc.noaa.gov/oa/climate/conversion/heatindexchart.html