Chicago 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.

	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

												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

Winter = Dec, Jan, and Feb		Spring = Mar, Apr, and May
Summer = Jun, Jul, and Aug.		Fall = Sep, Oct, and Nov