Weather in Cook County

Calculated from weather data of Chicago O'hare International Airport (KORD) between 2020 and 2024.

Maximum temperatures (°F)

Month	Average	2024	2023	2022	2021	2020
January	33.0	31.0	38.0	29.0	34.0	36.0
February	39.0	50.0	43.0	36.0	28.0	37.0
March	49.0	54.0	46.0	50.0	54.0	51.0
April	59.0		63.0	56.0	63.0	58.0
May	71.0		73.0	73.0	70.0	70.0
June	82.0		81.0	83.0	84.0	84.0
July	84.0		84.0	83.0	82.0	88.0
August	83.0		83.0	83.0	85.0	86.0
September	77.0		77.0	76.0	79.0	75.0
October	63.0		65.0	63.0	66.0	61.0
November	48.0		51.0	53.0	48.0	56.0
December	41.0		44.0	38.0	45.0	40.0
Average	59.0	45.0	62.0	61.0	62.0	62.0

Average highest temperature per day

The maximum temperature is typically observed some hours after noon.

Minimum temperatures (°F)

Month	Average	2024	2023	2022	2021	2020
January	22.0	23	28	14	26	25
February	23.0	31	27	20	14	24
March	33.0	37	33	33	37	35
April	41.0		42	41	44	40
May	53.0		53	56	52	52
June	63.0		62	64	66	65
July	69.0		68	68	67	71
August	67.0		67	67	69	68
September	61.0		62	60	62	59
October	48.0		51	45	54	44
November	35.0		36	37	34	41
December	29.0		35	29	32	28
Average	43.0	30.0	47.0	45.0	47.0	46.0

Average lowest temperature per day

The minimum temperature is typically observed just before sunrise.

Cold and hot days

Number of days	2024	2023	2022	2021	2020
86 °F or warmer	0	31	30	42	54
77 °F or warmer	0	109	108	112	111
68 °F or warmer	6	158	155	164	150
32 °F or colder	48	67	90	88	77

Precipitation (%)

Month	Average	2024	2023	2022	2021	2020
January	22.3	24	33	17	18	20
February	15.4	1	14	26	21	15
March	13.1	9	19	27	6	16
April	12.8		12	17	8	13
May	9.1		7	14	7	11
June	5.2		5	6	6	4
July	3.7		7	7	3	3
August	2.8		4	5	1	0
September	5.9		12	6	3	7
October	11.1		14	7	12	8
November	11.6		9	18	10	7
December	13.2		21	27	8	10
Average	10.2	11.1	12.4	13.8	7.8	9.0

Precipitation during daylight period

Percentage of observations with observed rain, drizzle, snow or hail. Only observations between sunrise and sunset are taken into account.

Wind speed (miles per hour)

Month	Average	2024	2023	2022	2021	2020
January	10.6	10	10	12	10	10
February	11.6	11	12	13	10	13
March	12.3	13	12	12	13	12
April	12.0		12	13	11	11
May	10.8		10	12	11	10
June	9.9		10	10	9	10
July	9.1		8	10	9	9
August	9.2		10	10	9	9
September	9.6		9	10	10	11
October	10.7		11	10	10	11
November	11.0		10	12	11	12
December	10.4		10	11	11	10
Average	10.7	11.5	10.2	11.0	10.3	10.6

Average wind speed

Excluding wind gusts. Only observations between sunrise and sunset are taken into account.

Prevailing wind direction

Month	2024	2023	2022	2021	2020
January	W	W	W	W	W
February	W	W	W	W	NW
March	W	NW	W	SW	SW
April		SW	SW	W	NW
May		NE	SE	SE	NE
June		NE	W	SW	S
July		NW	W	N	W
August		N	NW	S	W
September		SE	NW	SW	W
October		W	SW	N	W
November		SW	SW	SW	SW
December		SW	S	SW	W

Prevailing wind direction

Average wind direction, weighed by wind speed. Only observations between sunrise and sunset are taken into account.

Cook County weather Q&A

What is the warmest month in Cook County?

The warmest month is July with an average temperature of 84 °F over the past years.

What is the coldest month in Cook County?

The coldest month is January with an average daytime temperature of 33 °F in the past few years.

Which month is the wettest in Cook County?

Chance of precipitation is the highest in January with a probability of around 22.3 %.

Which month is the driest in Cook County?

The least rainfall and snow can be expected in August. The probability is about 2.9 %.