Weather in Cook County

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

Maximum temperatures (°C)

Month	Average	2024	2023	2022	2021	2020
January	0.4	-1.3	3.1	-2.1	1.0	2.2
February	4.0	9.9	6.0	2.1	-3.6	2.9
March	9.2	12.0	7.7	10.1	12.1	10.5
April	15.0		17.1	13.3	17.0	14.6
May	21.8		23.0	22.6	21.3	21.1
June	27.6		27.3	28.5	28.6	28.8
July	29.0		28.8	28.5	27.6	31.1
August	28.4		28.3	28.1	29.6	29.8
September	25.1		25.0	24.1	26.3	23.6
October	17.3		18.3	17.3	19.1	16.1
November	8.9		10.5	11.4	9.0	13.5
December	4.8		6.9	3.6	7.2	4.5
Average	14.8	6.9	16.9	16.1	16.5	16.6

Average highest temperature per day

The maximum temperature is typically observed some hours after noon.

Minimum temperatures (°C)

Month	Average	2024	2023	2022	2021	2020
January	-6.3	-5	-2	-10	-4	-4
February	-5.2	0	-3	-7	-10	-4
March	0.7	3	0	1	3	2
April	5.0		6	5	7	4
May	11.5		12	14	11	11
June	17.2		16	18	19	18
July	20.2		20	20	20	22
August	19.3		19	19	21	20
September	16.2		17	16	17	15
October	8.8		11	7	12	6
November	1.3		2	3	1	5
December	-2.2		2	-2	0	-2
Average	6.3	-2.9	8.3	7.2	8.1	7.8

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
30 °C or warmer	0	31	30	42	54
25 °C or warmer	0	109	108	112	111
20 °C or warmer	6	158	155	164	150
0 °C 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 (km/h)

Month	Average	2024	2023	2022	2021	2020
January	17.1	17	16	19	17	16
February	18.7	18	20	21	16	20
March	19.8	21	20	19	21	19
April	19.4		20	21	18	18
May	17.4		16	19	18	17
June	16.0		16	16	15	16
July	14.8		13	16	15	15
August	14.9		16	16	14	15
September	15.5		14	15	16	17
October	17.3		17	17	16	18
November	17.8		17	20	17	20
December	16.7		15	17	18	16
Average	17.2	18.6	16.4	17.8	16.7	17.0

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 29 °C over the past years.

What is the coldest month in Cook County?

The coldest month is January with an average daytime temperature of 0 °C 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 %.