National Weather Service United States Department of Commerce

Winter Storm Bringing Widespread Hazardous Weather to the Eastern U.S.

A rapidly-intensifying winter storm continues to bring heavy snow, high winds, and blizzard conditions over the Upper Midwest and Great Lakes through today. An Arctic front will lead in a period of gusty to high winds and sharply colder temperatures over the entire eastern U.S. Heavy lake effect snow is then expected from Lakes Erie and Ontario through New Year's Day. Read More >

HEAT INDEX °F (°C)
  RELATIVE HUMIDITY (%)
Temp. 40 45 50 55 60 65 70 75 80 85 90 95 100
110
(47)
136
(58)
                       
108
(43)
130
(54)
137
(58)
                     
106
(41)
124
(51)
130
(54)
137
(58)
                   
104
(40)
119
(48)
124
(51)
131
(55)
137
(58)
                 
102
(39)
114
(46)
119
(48)
124
(51)
130
(54)
137
(58)
               
100
(38)
109
(43)
114
(46)
118
(48)
124
(51)
129
(54)
136
(58)
             
98
(37)
105
(41)
109
(43)
113
(45)
117
(47)
123
(51)
128
(53)
134
(57)
           
96
(36)
101
(38)
104
(40)
108
(42)
112
(44)
116
(47)
121
(49)
126
(52)
132
(56)
         
94
(34)
97
(36)
100
(38)
103
(39)
106
(41)
110
(43)
114
(46)
119
(48)
124
(51)
129
(54)
135
(57)
     
92
(33)
94
(34)
96
(36)
99
(37)
101
(38)
105
(41)
108
(42)
112
(44)
116
(47)
121
(49)
126
(52)
131
(55)
   
90
(32)
91
(33)
93
(34)
95
(35)
97
(36)
100
(38)
103
(39)
106
(41)
109
(43)
113
(45)
117
(47)
122
(50)
127
(53)
132
(56)
88
(31)
88
(31)
89
(32)
91
(33)
93
(34)
95
(35)
98
(37)
100
(38)
103
(39)
106
(41)
110
(43)
113
(45)
117
(47)
121
(49)
86
(30)
85
(29)
87
(31)
88
(31)
89
(32)
91
(33)
93
(34)
95
(35)
97
(36)
100
(38)
102
(39)
105
(41)
108
(42)
112
(44)
84
(29)
83
(28)
84
(29)
85
(29)
86
(30)
88
(31)
89
(32)
90
(32)
92
(33)
94
(34)
96
(36)
98
(37)
100
(38)
103
(39)
82
(28)
81
(27)
82
(28)
83
(28)
84
(29)
84
(29)
85
(29)
86
(30)
88
(31)
89
(32)
90
(32)
91
(33)
93
(34)
95
(35)
80
(27)
80
(27)
80
(27)
81
(27)
81
(27)
82
(28)
82
(28)
83
(28)
84
(29)
84
(29)
85
(29)
86
(30)
86
(30)
87
(31)

Category Heat Index Possible heat disorders for people in high risk groups
Extreme
Danger
130°F or higher
(54°C or higher)
Heat stroke or sunstroke likely.
Danger 105 - 129°F
(41 - 54°C)
Sunstroke, muscle cramps, and/or heat exhaustion likely. Heatstroke possible with prolonged exposure and/or physical activity.
Extreme
Caution
90 - 105°F
(32 - 41°C)
Sunstroke, muscle cramps, and/or heat exhaustion possible with prolonged exposure and/or physical activity.
Caution 80 - 90°F
(27 - 32°C)
Fatigue possible with prolonged exposure and/or physical activity.