Weather Averages Alton, IL

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Weather Averages for
Alton, IL


Latitude: 38°52'N, Longitude: 90°10'W, Elevation: 430.0 ft, Distance: 5.54 mi

  Unit Year Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Average temperature
over 30 years
°F 54 26 31 42 54 64 74 78 76 68 56 44 32
Average high temperature
over 30 years
°F 64 36 40 52 64 74 84 88 86 79 67 53 40
Average low temperature
over 30 years
°F 44 17 21 32 44 54 64 68 66 57 46 35 23
Highest recorded temperature
over 49 years
°F 111 71 75 84 91 98 107 111 105 102 93 84 73
Lowest recorded temperature
over 49 years
°F -16 -16 -14 0 19 32 44 50 46 37 24 3 -16
Average number of days above 90°F
over 30 years
days 37 - - - 0.1 1.1 7.3 14 10 3.4 0.2 - -
Average precipitation
over 30 years
in 38.4 1.9 2.1 3.6 3.7 4.3 3.3 3.7 3.3 3.1 2.8 3.4 3.2
Average number of days below 32°F
over 30 years
days 103 27 22 16 2.2 - - - - - 1.3 12 23
Average number of days below 0°F
over 30 years
days 3.4 1.8 0.8 - - - - - - - - - 0.7
Average snowfall
over 30 years
in 11.9 4.4 4.3 2.9 0.4 - - - - - - 0.5 1.5
Most rain reported in a day
over 54 years
in 7.7 3.6 2.3 4.1 7.7 4.7 3.4 4.7 4.3 3.5 3.5 5.4 2.7
Most rain reported in a month
over 54 years
in 53.7 7.8 5.7 8.1 17.5 10.2 10.8 9.6 14.8 11.5 7.1 12.8 8.2
Least rain reported in a month
over 54 years
in 19.1 0.1 - 0.9 0.8 1.0 0.4 0.3 0.5 0.3 0.3 0.2 0.2
Heating degree days
over 30 years
days 5189 1174 957 691 323 101 6 1 2 48 277 604 1005
Cooling degree days
over 30 years
days 1343 - - 2 19 96 279 415 344 163 25 - -
Most snow reported in a month
over 54 years
in 45.6 18.8 19.5 24.6 5.5 - - - - - - 9.8 8.7