Chicago has four distinct seasons: cold, snowy winters and warm, humid summers. Under the National Weather Service’s 1991–2020 normals, July is the warmest month with an average high of 84.5°F, January is the coldest with an average low of 18.8°F, and the city gets about 37.9 inches of precipitation and 38.4 inches of snow a year. Late spring through early fall is the most comfortable time to visit.
| Measure (1991–2020 normals) | Value |
|---|---|
| Warmest month | July: average high 84.5°F, low 66.4°F |
| Coldest month | January: average high 31.6°F, low 18.8°F |
| Wettest month | May: 4.49 inches |
| Snowiest month | January: 11.3 inches |
| Annual precipitation | 37.86 inches |
| Annual snowfall | 38.4 inches |
| Annual mean temperature | 51.2°F |
| Record high | 105°F on July 24, 1934 |
| Record low | −27°F on January 20, 1985 |
| Record one-day snowfall | 18.6 inches on January 2, 1999 |
Chicago weather by month
These are the official National Weather Service Chicago normals for 1991–2020. Temperatures are in degrees Fahrenheit and precipitation and snowfall in inches. “T” means a trace.
| Month | Avg high (°F) | Avg low (°F) | Precipitation (in.) | Snowfall (in.) |
|---|---|---|---|---|
| January | 31.6 | 18.8 | 1.99 | 11.3 |
| February | 35.7 | 21.8 | 1.97 | 10.7 |
| March | 47.0 | 31.0 | 2.45 | 5.5 |
| April | 59.0 | 40.3 | 3.75 | 1.3 |
| May | 70.5 | 50.6 | 4.49 | T |
| June | 80.4 | 60.8 | 4.10 | 0.0 |
| July | 84.5 | 66.4 | 3.71 | 0.0 |
| August | 82.5 | 65.1 | 4.25 | 0.0 |
| September | 75.5 | 57.1 | 3.19 | 0.0 |
| October | 62.7 | 45.4 | 3.43 | 0.2 |
| November | 48.4 | 34.1 | 2.42 | 1.8 |
| December | 36.6 | 24.4 | 2.11 | 7.6 |
| Year | 59.5 | 43.0 | 37.86 | 38.4 |
The seasons
Winter (December–February)
Average highs stay in the 30s from December through February, and lows average in the high teens and low 20s. January and February each average more than 10 inches of snow. Wind off the lake and across open plazas makes it feel colder than the thermometer says.
Spring (March–May)
Spring warms quickly, from an average high of 47°F in March to 70.5°F in May. It is also the wettest stretch: April and May together average more than 8 inches of rain. Near the lake, spring days can be noticeably cooler than inland.
Summer (June–August)
Summer is warm and often humid, with average highs of 80.4°F in June, 84.5°F in July and 82.5°F in August. Thunderstorms are common, and August averages 4.25 inches of rain. This is beach, festival and baseball season.
Fall (September–November)
September averages a high of 75.5°F and is often the most pleasant month of the year. October cools to an average high of 62.7°F, and November drops to 48.4°F. November averages 1.8 inches of snow, and October sees only a trace on average (0.2 inch).
Lake Michigan’s effect on the weather
Lake Michigan warms and cools more slowly than land. In spring and early summer, it cools a narrow strip of the city along the shore, about a mile inland, which is the source of the forecast phrase “cooler by the lake.” The change is gradual rather than a sharp line.
By late summer the water has warmed and the cooling stops. In fall and early winter the pattern flips, and the lakefront runs slightly warmer than inland neighborhoods into January.
Lake-effect snow
Lake-effect snow forms when cold air crosses the warmer lake, picks up moisture and drops it as snow on the far shore. With typical winter winds, that is usually Northwest Indiana and western Michigan, not Chicago. The city gets heavy lake-effect snow only when winds turn to blow from the lake toward the city, as during the Groundhog Day blizzard of February 2011.
Is Chicago really the Windy City?
Not especially. WTTW reports that Chicago ranks only about 12th among U.S. cities for wind. The nickname appeared in print by 1876 and probably always had a double meaning, covering both the weather and boastful local talk. Wind off the lake can still make winter days feel harsher. See Chicago at a glance for the nickname’s history.
Best time to visit Chicago
- June through September brings average highs from the mid-70s to mid-80s, beaches, outdoor festivals and lakefront activity. Expect peak crowds and hotel prices.
- May and October offer milder temperatures (average highs of about 70°F and 63°F) and fewer crowds, but pack for changeable weather.
- December brings the holiday season, with average highs in the mid-30s.
- January and February are the coldest months; they suit museums, theater and indoor dining, and often bring lower hotel rates.
Check Chicago events and things to do for what’s on during your dates.
What to pack
| Season | Pack |
|---|---|
| Winter | Insulated, wind-resistant coat, hat, gloves, scarf and waterproof boots with good grip |
| Spring | Layers, a rain jacket or umbrella, and a warmer layer for lakefront days |
| Summer | Light clothing, sunscreen, a light layer for air-conditioned spaces, and an umbrella for storms |
| Fall | Layers, a medium jacket, and a hat and gloves by November |
Year-round, bring comfortable walking shoes. Chicago is a walking and transit city, and you may cover several miles a day. Our getting around guides explain the ‘L’, buses and Divvy bikes.
Frequently asked questions
What is the coldest month in Chicago?
January, with an average high of 31.6°F and an average low of 18.8°F under the 1991–2020 normals.
What is the hottest month in Chicago?
July, with an average high of 84.5°F and an average low of 66.4°F.
How much snow does Chicago get?
About 38.4 inches in an average year. January (11.3 inches) and February (10.7 inches) are the snowiest months.
What is the best month to visit Chicago?
For warm weather and outdoor events, June through September. September often has the best mix of warmth (average high 75.5°F) and smaller crowds.
What does “cooler by the lake” mean?
In spring and early summer, cold Lake Michigan water chills the shore, so lakefront areas are cooler than inland neighborhoods. The effect reaches about a mile inland.
What is Chicago’s record high temperature?
105°F, set on July 24, 1934. The record low is −27°F, set on January 20, 1985.
Related guides
- Chicago at a glance
- Geography and layout
- Chicago events
- Outdoors and the lakefront
- Things to do
- Chicago FAQ
Sources
- National Weather Service Chicago: 1991–2020 monthly and annual normals
- National Weather Service Chicago: Climate records and rankings
- WBEZ Curious City: When is it no longer cooler by the lake?
- WTTW News: Where did Chicago’s nicknames come from?
Last updated: October 31, 2026