Chicago, Illinois Climate Records and Averages

    Chicago is located along the southwest shore of Lake Michigan and is in a region of frequently changeable weather. The climate is predominately continental, ranging from winters with bitter winds to occasional muggy summer heat waves. During the warm season, when the lake is cold relative to land, there is frequently a lake breeze that reduces daytime temperatures near the shore, sometimes by 10 degrees or more below temperatures farther inland. At the O'Hare International Airport temperatures of 96 degrees or higher occur in about half the summers, while about half the winters have a minimum as low as −15 degrees. The average occurrence of the first temperature as low as 32 degrees in the fall is mid–October and the average occurrence of the last temperature as low as 32 degrees in the spring is late April.

Summer thunderstorms are often locally heavy and variable, parts of the city may receive substantial rainfall and other parts none. Longer periods of continuous precipitation are mostly in autumn, winter, and spring. About one–half the precipitation in winter, and about 10 percent of the yearly total precipitation, falls as snow. Snowfall from month to month and year to year is greatly variable. There is a 50 percent likelihood that the first and last l–inch snowfall of a season will occur by December 5 and March 20, respectively.

Although winds can be strong in Chicago, the nickname of "The Windy City"  is a misnomer as the average wind speed is not greater than in many other parts of the United States. Of the 262 major weather reporting stations in the United States, 27% or 72 stations average higher annual wind speeds than Chicago, which averages 10.3 mph. For example, New York City's annual wind speed is 12.2 mph.

Temperature + Precipitation 

  Monthly Averages Daily Extremes Monthly Extremes Max. Temp. Min. Temp.  
Temperatures
 in F
Max. Min. Avg High Date of 
daily extreme
 high
Low Date of
daily extreme
low
Highest
Avg
Year Lowest
Avg
Year # Days >=
90 F
# Days <=
32 F
# Days <=
32 F
# Days <=
0 F
January 29.8 14.7 22.2 65 31/1989 -27 20/1985 35.8 2006 10.7 1977 0.0 17.3 28.5 5.5
February 34.3 18.7 26.5 71 27/1976 -19 03/1996 38.7 1998 16.2 1979 0.0 12.3 25.0 2.5
March 45.7 28.4 37.0 88 29/1986 -8 01/1962 44.9 1977 24.4 1960 0.0 3.8 20.8 0.2
April 58.8 38.7 48.8 91 22/1980 7 07/1982 55.0 1977 43.3 1975 0.0 0.1 7.2 0.0
May 70.0 48.2 59.1 93 19/1977 24 10/1966 67.2 1977 53.2 1983 0.7 0.0 0.7 0.0
June 79.6 57.8 68.7 104 20/1988 36 22/1963 74.2 2005 62.0 1982 3.8 0.0 0.0 0.0
July 83.7 63.2 73.4 104 13/1995 40 01/1965 78.3 1999 68.4 1967 6.3 0.0 0.0 0.0
August 81.9 62.2 72.1 101 02/1991 41 15/1964 79.0 1995 66.1 1967 4.1 0.0 0.0 0.0
September 75.0 54.2 64.6 99 07/1960 28 23/1974 69.7 1971 59.2 1993 1.6 0.0 0.2 0.0
October 62.8 42.7 52.7 91 06/1963 17 24/1981 61.6 1971 46.0 1988 0.0 0.0 4.5 0.0
November 48.2 32.0 40.1 78 05/1978 1 30/1958 48.2 2001 31.8 1959 0.0 2.0 15.7 0.0
December 34.7 20.3 27.5 71 02/1982 -25 24/1983 35.9 1982 13.2 1963 0.0 11.7 26.5 2.3
Annual 58.7 40.1 49.4 104 1988/06/20 -27 1985/01/20 53.5 1998 47.0 1985 16.5 47.1 129.1 10.5
Winter 32.9 17.9 25.4 71 1976/02/27 -27 1985/01/20 33.2 1998 17.2 1963 0.0 41.2 80.0 10.3
Spring 58.2 38.4 48.3 93 1977/05/19 -8 1962/03/01 55.7 1977 43.6 1984 0.7 3.9 28.7 0.2
Summer 81.7 61.1 71.4 104 1988/06/20 36 1963/06/22 76.3 1995 67.1 1992 14.1 0.0 0.0 0.0
Fall 62.0 43.0 52.5 99 1960/09/07 1 1958/11/30 57.7 1971 47.8 1976 1.6 2.0 20.4 0.0

Precipitation

    Total Snowfall
  Avg. High Year Low Year 1 Day Max. >=
0.01 in.
>=
0.10 in.
>=
0.50 in.
>=
1.00 in.
Mean High Year
  in. in. - in. - in. dd/yyyy
or
yyyymmdd
# Days # Days # Days # Days in. in. -
January 1.72 4.47 1999 0.10 1981 2.00 12/1960 11 5 1 0 11.1 34.3 1979
February 1.56 5.56 1997 0.12 1969 3.44 21/1997 9 4 1 0 8.1 26.2 1994
March 2.57 5.91 1976 0.63 1981 1.75 04/1985 12 6 1 0 6.1 24.7 1965
April 3.55 7.69 1983 0.74 2004 2.37 20/2000 12 7 2 1 1.4 11.1 1975
May 3.45 7.22 2004 0.30 1992 3.45 29/1981 11 7 2 1 0.0 1.6 1966
June 3.76 9.96 1993 0.76 2005 3.97 19/2009 10 6 3 1 - - -
July 3.59 8.84 2010 1.18 1977 3.64 24/2010 10 6 2 1 - - -
August 4.35 17.10 1987 0.51 1969 6.49 14/1987 9 6 3 1 - - -
September 3.51 13.63 2008 0.02 1979 6.64 13/2008 9 6 2 1 - - -
October 2.73 8.54 2001 0.16 1964 4.25 10/1969 10 5 2 1 0.3 6.6 1967
November 2.69 8.22 1985 0.44 1999 2.93 27/1990 11 6 2 1 1.7 10.4 1959
December 2.22 8.56 1982 0.23 1962 4.47 02/1982 11 5 1 0 8.4 35.3 1978
 
Annual 35.70 50.86 2008 21.77 1962 6.64 2008/09/13 125 69 22 8 37.2 75.0 1978
 
Winter 5.51 11.28 1983 1.43 1963 4.47 1982/12/02 31 14 3 1 27.6 76.4 1979
Spring 9.57 17.51 1983 3.87 1994 3.45 1981/05/29 35 20 6 2 7.6 24.9 1982
Summer 11.70 23.48 1987 5.08 1991 6.49 1987/08/14 29 19 8 3 - - -
Fall 8.93 17.51 2008 3.10 1962 6.64 2008/09/13 29 17 6 2 2.0 10.7 1959
Illinois averages and extremes in precipitation and temperature and Top 10 U.S climate extremes.
Winter = Dec, Jan, and Feb Spring = Mar, Apr, and May
Summer = Jun, Jul, and Aug. Fall = Sep, Oct, and Nov
Data period is 1958-2010, Chicago O'Hare Airport (ORD). Source: Western Regional Climate Center