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Climate in Chicago, Illinois: Monthly Weather Averages

By the AverageClimate Editorial Team · Last updated: October 2026

Chicago sits at 658 feet above sea level, and its climate, as recorded at the Chicago Ohare International Airport, IL station, runs to a yearly mean of 51.3°F. The warmest month is July, averaging 75.4°F with typical highs of 84.5°F; the coldest is January, averaging 25.2°F with lows around 18.8°F. Across a normal year the city receives 37.9 in of precipitation and 38.4 in of snow. The full month-by-month picture below comes from the official 1991–2020 U.S. Climate Normals — the 30-year averages the National Weather Service itself uses — so it describes the Chicago climate you should actually plan around, whether you are timing a visit, weighing a move, or just settling an argument about which month is best.

Chicago climate month by month

The table below is the complete 1991–2020 normals profile for Chicago: average high, average low and mean temperature, rainfall, and snowfall for every month. Read down the Mean column to feel the year's rhythm — Chicago's temperature range runs from 25.2°F in January to 75.4°F in July.

How to read the colors:below freezingcoldcoolmildwarmhot. Bands are colored by each cell's own temperature, so a whole year reads at a glance.

Chicago through the seasons

Winter in Chicago averages highs of 31.6–36.6°F and lows of 18.8–24.4°F, a seasonal mean of 28.2°F. The three months together bring 6.1 in of precipitation — about 16% of the city's yearly total — with December the wettest of the three at 2.11 in. Snowfall averages 29.6 in over the season, most of it in January (11.3 in). Average temperatures sit below freezing, so this is the heart of the heating season: expect snow-covered ground, icy mornings, and short, cold days as the local norm rather than the exception.

Spring in Chicago averages highs of 47.0–70.5°F and lows of 31.0–50.6°F, a seasonal mean of 49.8°F. The three months together bring 10.7 in of precipitation — about 28% of the city's yearly total — with May the wettest of the three at 4.49 in. Snowfall averages 6.8 in over the season, most of it in March (5.5 in). The season is a transition: the average temperature climbs 21.6°F from March to May, and by late spring Chicago is firmly into mild territory, with May rainfall of 4.49 in to plan around.

Summer in Chicago averages highs of 80.4–84.5°F and lows of 60.8–66.4°F, a seasonal mean of 73.3°F. The three months together bring 12.1 in of precipitation — about 32% of the city's yearly total — with August the wettest of the three at 4.25 in. It is a warm, usable summer: afternoons are hot enough for swimming and lake or coast time, while evenings usually cool off comfortably.

Fall in Chicago averages highs of 48.4–75.5°F and lows of 34.1–57.1°F, a seasonal mean of 53.9°F. The three months together bring 9.0 in of precipitation — about 24% of the city's yearly total — with October the wettest of the three at 3.43 in. Snowfall averages 2.0 in over the season, most of it in November (1.8 in). Temperatures ease off through the season — the monthly mean drops 25.0°F from September to November — and fall is when Chicago's weather turns crisp and dry, while nights stay mostly frost-free into December.

Best and worst months to visit Chicago

Ranking every month by its normals — mild mean temperatures score best, heavy rain and snow count against — the most comfortable months to visit Chicago are:

JuneAugustSeptember

June leads the list: average highs of 80.4°F, lows of 60.8°F, and 4.10 in of rain, with snow a non-factor at 0.0 in. The other picks, August and September, offer the same balance in Chicago's mild stretch of the year. At the other end, January is usually the month to avoid — deep-winter cold, with a mean temperature of 25.2°F and 1.99 in of precipitation plus 11.3 in of snow.

How Chicago compares

Across the 114 cities in our dataset, the typical city averages 57.8°F for the year and 35.7 in of precipitation. Chicago runs 6.5°F cooler than that typical city and wetter by 2.2 in a year, ranking #84 of 114 for annual warmth and #59 of 114 for precipitation (wettest first). Its year-round temperature swing — warmest month minus coldest — is 50.2°F, which puts it in the strongly continental, four-real-seasons camp.

Planning notes for Chicago

For anyone relocating: average overnight lows drop below freezing in 4 months (January, February, March, December), so heating, winter tires, and pipe protection are real seasonal concerns; highs reach the 80s on average in 3 months, but 90°F average highs never arrive; 5 months of the year average between 55°F and 80°F, the band most people find comfortable without heating or cooling. Those four facts, all straight from the normals table above, shape everything from a Chicago wardrobe to its utility bills.

Chicago climate FAQ

Source: 1991–2020 U.S. Climate Normals, NOAA National Centers for Environmental Information (NCEI) — ncei.noaa.gov. Station: Chicago Ohare International Airport, IL (USW00094846), elevation 658 ft. Figures checked October 2026.