Chicago, IL Weather
Chicago hourly forecast: next 24 hours
Today's high of 81°F (27°C) is about 6°F (3°C) above the typical September high of 75°F (24°C).
Current conditions in detail
Chicago weather tomorrow (Friday, September 18)
Tomorrow in Chicago looks partly cloudy, with a high of 76° and an overnight low of 65°. There is a 57% chance of rain - plan accordingly. Winds top out near 10 mph, and the UV index reaches 3 (low).
Chicago 14-day forecast
About the weather in Chicago
The Chicago year is defined by how long its winter lasts: 4 months average sub-freezing nights, bottoming out in January at 20°F (-6°C). Summer is the short exception, with July reaching 80°F (27°C).
Chicago weather: quick facts
- Hottest month: July - highs near 80°F (27°C)
- Coldest month: January - highs near 32°F (0°C)
- Decade extremes (2015-2024): 99°F (37°C) high · -26°F (-32°C) low
- Wettest month: July (12 rainy days) · Sunniest: July (11.8 h sun/day)
- Climate type: humid continental
- Annual swing: 26°C between the average warmest and coolest month · day to night: 8°C
- Snow: about 18 days a year
- Months with freezing average lows: 4
- Average humidity: 74%
Temperatures through the year
Precipitation concentrates in July - 6.0 inches (152 mm) on 12 days - and thins out by February. January bottoms out at 32°F (0°C) in daylight, 20°F (-6°C) after dark. At its warmest, in July, Chicago runs to 80°F (27°C) in the afternoon and back to 67°F (19°C) by dawn. Across the gridded 2015-2024 daily record, the highest daily maximum for this location was 99°F (37°C) and the lowest daily minimum -26°F (-32°C). Between the average July and the average January lie 26°C, a wider spread than roughly 88% of the cities we track.
Rain, sun and snow
Sunshine averages 8.5 hours a day over the year, peaking in July at 11.8 hours. Overnight lows average at or below freezing for 4 months, December through March.
Season by season
Spring (March through May)
Spring is mild here - highs near 55°F (13°C), nights near 40°F (5°C), and rain falls on around 38 of the 90 days, plus about 4 snowy days.
Summer (June through August)
Summer in Chicago settles into easy warmth, with daytime highs averaging 79°F (26°C) and nights around 65°F (18°C); rain falls on around 36 of the 90 days. Daylight is generous - around 11.6 hours of sun a day.
Fall (September through November)
Fall runs cool rather than cold here - highs near 62°F (16°C), nights near 49°F (9°C), and expect showers on roughly 30 days across the season.
Winter (December through February)
Through winter, Chicago is bitterly cold: 36°F (2°C) by day, 23°F (-5°C) after dark, and expect showers on roughly 28 days across the season, plus about 13 snowy days. Wind sharpens cold like this considerably; pair the forecast winds with the wind speed converter to judge exposed conditions.
Average temperatures in Chicago by month
| Month | High | Low | Rain days | Precipitation | Sunshine | Humidity |
|---|---|---|---|---|---|---|
| January | 32° | 20° | 10 | 2.6 in | 4.9 h/day | 76% |
| February | 36° | 20° | 9 | 2.4 in | 6.8 h/day | 73% |
| March | 45° | 31° | 11 | 3.5 in | 7.9 h/day | 74% |
| April | 54° | 39° | 14 | 4.2 in | 8.8 h/day | 73% |
| May | 66° | 50° | 13 | 5.3 in | 10.1 h/day | 76% |
| June | 77° | 61° | 12 | 4.5 in | 11.6 h/day | 73% |
| July | 80° | 67° | 12 | 6.0 in | 11.8 h/day | 77% |
| August | 80° | 66° | 12 | 4.2 in | 11.5 h/day | 76% |
| September | 75° | 62° | 10 | 3.8 in | 9.6 h/day | 74% |
| October | 62° | 49° | 12 | 4.8 in | 7.5 h/day | 72% |
| November | 48° | 36° | 8 | 2.5 in | 6.0 h/day | 73% |
| December | 39° | 28° | 9 | 2.6 in | 5.0 h/day | 75% |