Chicago O’Hare International Airport Climate Normals

Official 1981-2010 Climate Normals

City: CHICAGO OHARE AP
State: IL
ID: 094846
Latitude: 41.9950
Longitude: -87.9336
Elevation:  658.0 ft

Temperature-Related Normals

Normal    Jan    Feb    Mar    Apr    May    Jun    Jul    Aug    Sep    Oct    Nov    Dec
High:    31.0   35.3   46.6   59.0   70.0   79.7   84.1   81.9   74.8   62.3   48.2   34.8
Mean:    23.8   27.7   37.9   48.9   59.1   68.9   74.0   72.4   64.6   52.5   40.3   27.7
 Low:    16.5   20.1   29.2   38.8   48.3   58.1   63.9   62.9   54.3   42.8   32.4   20.7
 CDD:       0      0      1      9     44    165    283    238     92     11      0      0
 HDD:    1279   1044    841    492    225     48      4      9    105    397    741   1155

Number of Days
T090:     0.0    0.0    0.0    0.0    0.5    3.0    5.9    3.6    1.0    0.0    0.0    0.0
T100:     0.0    0.0    0.0    0.0    0.0    0.1    0.3    0.0    0.0    0.0    0.0    0.0
T000:     3.8    1.7    0.0    0.0    0.0    0.0    0.0    0.0    0.0    0.0    0.0    1.5
T032:    28.0   24.0   19.6    6.3    0.3    0.0    0.0    0.0    0.1    3.5   14.0   26.0
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Annual Values

 High Temp:    59.1 F
 Mean Temp:    49.9 F
  Low Temp:    40.8 F
Cooling DD:     842
Heating DD:    6339

Days above  90 (T090):    14.0
Days above 100 (T100):     0.4
Days below   0 (T000):     7.1
Days below  32 (T032):   121.8
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Precipitation-Related Normals

Normal    Jan    Feb    Mar    Apr    May    Jun    Jul    Aug    Sep    Oct    Nov    Dec
Prcp:    1.73   1.79   2.50   3.38   3.68   3.45   3.70   4.90   3.21   3.15   3.15   2.25
Snow:    10.8    9.1    5.6    1.2    0.0    0.0    0.0    0.0    0.0    0.3    1.2    8.5

Number of Days
P001:    10.5    8.8   11.1   12.0   11.6   10.2    9.8    9.8    8.3   10.2   10.8   11.0
P010:     4.7    4.4    5.5    6.4    7.2    5.9    6.0    6.7    5.4    5.9    6.0    5.0
P100:     0.1    0.3    0.4    0.8    0.8    0.9    1.0    1.5    0.8    0.6    0.8    0.3
S001:     8.2    6.1    4.3    0.9    0.0    0.0    0.0    0.0    0.0    0.2    1.7    7.1
S010:     3.7    2.8    1.7    0.3    0.0    0.0    0.0    0.0    0.0    0.1    0.4    2.6
S100:     0.0    0.1    0.0    0.0    0.0    0.0    0.0    0.0    0.0    0.0    0.0    0.0
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Annual Values

Precipitation:   36.89 inches
     Snowfall:    36.7 inches

   Days precipitation at or above 0 inches (P000):   124.1
Days precipitation at or above 0.10 inches (P010):    69.1
Days Precipitation at or above 1.00 inches (P100):     8.3
      Days Snowfall at or above 0.1 inches (S001):    28.5
      Days Snowfall at or above 1.0 inches (S010):    11.6
     Days Snowfall at or above 10.0 inches (S100):     0.1

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KEY:
High - average daily high temperature, degrees F
Mean - average daily mean temperature, degrees F
Low - average daily low temperature, degrees F
CDD - cooling degree days, base 50F
HDD - heating degree days, base 50F
T090 - number of Days with Temperatures above 90 degrees F
T100 - number of Days with Temperatures above 100 degrees F
T000 - number of Days with Temperatures below 0 degrees F
T032 - number of Days with Temperatures below 32 degrees F
Prcp - precipitation, inches
Snow - snowfall, inches
P001 - number of Days with Precipitation of 0.01 inches or more
P010 - number of Days with Precipitation of 0.10 inches or more
P100 - number of Days with Precipitation of 1.00 inches or more
S001 - number of Days with Snowfall of 0.1 inches or more
S010 - number of Days with Snowfall of 1.0 inches or more
S100 - number of Days with Snowfall of 10.0 inches or more

Page Source:
Dr. Jim Angel, State Climatologist
Illinois State Water Survey
Prairie Research Institute
University of Illinois

Data Source:
NOAA National Climatic Data Center