IL · climate averages
Chicago Weather by Month
These are climate averages, not a forecast. Station Chicago O'Hare Intl AP (USW00094846), 17.5 miles from downtown, elevation 658 ft.
Chicago's warmest month is July (avg high 84.5°F), coldest is January (avg low 18.8°F) and wettest is May (4.49 in), per NOAA 1991–2020 climate normals.
- Warmest high July 84.5°F
- Coldest low January 18.8°F
- Wettest month May 4.49 in
- Year of rain 12 months 37.86 in
Monthly Averages
Chicago's 12 monthly precipitation normals add up to 37.86 inches a year.
February is the driest month, with a precipitation normal of 1.97 inches.
January, February, March, April, October, November and December are the months with a snowfall normal above 0.1 inch, and they sum to 38.4 inches.
Chicago averages 125.8 days a year with at least 0.01 inch of precipitation.
| Month | Avg high | Avg low | Precipitation | Days ≥ 0.01 in | Snow |
|---|---|---|---|---|---|
| January | 31.6°F | 18.8°F | 1.99 in | 11.0 | 11.3 in |
| February | 35.7°F | 21.8°F | 1.97 in | 9.4 | 10.7 in |
| March | 47.0°F | 31.0°F | 2.45 in | 10.8 | 5.5 in |
| April | 59.0°F | 40.3°F | 3.75 in | 12.3 | 1.3 in |
| May | 70.5°F | 50.6°F | 4.49 in | 12.5 | 0.0 in |
| June | 80.4°F | 60.8°F | 4.10 in | 11.1 | 0.0 in |
| July | 84.5°F | 66.4°F | 3.71 in | 9.7 | 0.0 in |
| August | 82.5°F | 65.1°F | 4.25 in | 9.4 | 0.0 in |
| September | 75.5°F | 57.1°F | 3.19 in | 8.5 | 0.0 in |
| October | 62.7°F | 45.4°F | 3.43 in | 10.5 | 0.2 in |
| November | 48.4°F | 34.1°F | 2.42 in | 10.0 | 1.8 in |
| December | 36.6°F | 24.4°F | 2.11 in | 10.6 | 7.6 in |
Warmest, Coldest and Wettest Months
The warmest month is July, with an average high of 84.5°F.
The coldest month is January, with an average low of 18.8°F.
The wettest month is May, at 4.49 inches of precipitation over about 12.5 days.
In Chicago, five months (May, June, July, August and September) have an average high of at least 70°F.
The range from the lowest average low to the highest average high in Chicago is 65.7°F.
In July, the average high in Chicago is 18.1°F above the average low.
Best Months to Visit Chicago for Weather
No month in Chicago meets the weather rule on this page, an average high from 65 to 85°F and precipitation below 3.16 inches.
The rule keeps a month when the average high is from 65 to 85°F and precipitation is below 3.16 inches, the mean of the twelve monthly precipitation normals.
About This Data
Source: NOAA National Centers for Environmental Information (NCEI), U.S. Climate Normals 1991–2020. Station: CHICAGO OHARE INTL AP (USW00094846), 17.5 mi from downtown, elevation 658 ft. Climate normals are 30-year averages, not forecasts. MonthSky is not affiliated with NOAA.
Palecki, Michael; Durre, Imke; Applequist, Scott; Arguez, Anthony; Lawrimore, Jay (2021). U.S. Climate Normals 2020: U.S. Monthly Climate Normals (1991-2020). NOAA National Centers for Environmental Information. Dataset. https://doi.org/10.25921/wck8-er13. Accessed 2026-10-21.
U.S. Government work.
NOAA and NCEI cannot provide any warranty as to the accuracy, reliability, or completeness of furnished data. Users assume responsibility to determine the usability of these data. The user is responsible for the results of any application of this data for other than its intended purpose.
NOAA and NCEI make no warranty, expressed or implied, regarding these data, nor does the fact of distribution constitute such a warranty. NOAA and NCEI cannot assume liability for any damages caused by any errors or omissions in these data. If appropriate, NCEI can only certify that the data it distributes are an authentic copy of the records that were accepted for inclusion in the NCEI archives.
These pages are built automatically from public NOAA data.
U.S. Monthly Climate Normals (1991-2020) dataset
NCEI dataset landing page for the monthly normals
FAQ
What is the hottest month in Chicago?
July is the warmest, with an average high of 84.5°F.
What is the wettest month in Chicago?
May is the wettest, at 4.49 inches over about 12.5 days.
How many rainy days does Chicago get a year?
The monthly counts of days with at least 0.01 inch of precipitation add up to 125.8 days.
When is the best time to visit Chicago for weather?
No month meets the rule used on this page: average high from 65 to 85°F and precipitation below the monthly mean of 3.16 inches.