Monthly climate guide
Chicago weather in September
September in Chicago is typically warm, with average daytime highs around 22°C (72°F) and night-time lows near 17°C (62°F). The month usually brings about 85 mm of rain (some rain) and is a mix of sun and cloud. Daytime highs are 3°C cooler than August and 7°C warmer than October.
What stands out in September
- Chicago is usually about 4°C cooler than Indianapolis, 270 km away, in September.
- September is Chicago's third warmest month.
- Days and nights are close, only about 5°C apart.
- Temperatures are falling — expect highs around 7°C lower by October.
Avg high
22°C
72°F
Avg low
17°C
62°F
Rainfall
85 mm
some rain
Humidity
77%
relative
Sky
48%
cloud · a mix of sun and cloud
Chicago weather by month
Show the monthly averages as a table
| Month | Avg high | Avg low | Rain | Humidity | Cloud cover |
|---|---|---|---|---|---|
| January | 0°C / 31°F | -5°C / 22°F | 48 mm | 86% | 70% |
| February | 0°C / 32°F | -6°C / 22°F | 61 mm | 85% | 71% |
| March | 5°C / 40°F | -1°C / 30°F | 57 mm | 82% | 65% |
| April | 10°C / 49°F | 3°C / 38°F | 108 mm | 81% | 65% |
| May | 15°C / 60°F | 9°C / 49°F | 129 mm | 83% | 65% |
| June | 21°C / 70°F | 15°C / 59°F | 113 mm | 82% | 57% |
| July | 25°C / 77°F | 20°C / 68°F | 93 mm | 79% | 47% |
| August | 25°C / 77°F | 20°C / 68°F | 95 mm | 76% | 46% |
| September | 22°C / 72°F | 17°C / 62°F | 85 mm | 77% | 48% |
| October | 15°C / 60°F | 10°C / 49°F | 107 mm | 78% | 59% |
| November | 8°C / 47°F | 3°C / 37°F | 59 mm | 80% | 63% |
| December | 3°C / 38°F | -1°C / 30°F | 53 mm | 85% | 73% |
What to pack for September
- T-shirts plus a light layer for the evening
- Comfortable trainers or sandals for long walks
- A compact umbrella or packable rain jacket
- Water-resistant shoes
Is September a good time to visit Chicago?
Our Chicago guide recommends: May to June or September to October, avoiding the bitter winter cold and the most humid days of summer.
A river or lake architecture boat tour is one of the best ways to see the skyline that made Chicago famous for its buildings.
Best time to visit Chicago →Other United States cities in September
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Chicago weather in September. WeatherCompare, 2026 (NASA POWER / ERA5, 2011–2020 monthly averages). https://weathercompare.eu/weather/usa/chicago/september
<a href="https://weathercompare.eu/weather/usa/chicago/september">Chicago weather in September</a> (WeatherCompare)
<iframe src="https://weathercompare.eu/embed/usa/chicago" width="300" height="160" style="border:0;border-radius:12px" loading="lazy" title="Chicago weather in September"></iframe> <p style="font-size:12px"><a href="https://weathercompare.eu/weather/usa/chicago/september">Chicago weather in September</a> – WeatherCompare</p>
Chicago in September: quick answers
Is September a good time to visit Chicago?
Yes. September is one of the best months for Chicago, with highs around 22°C and about 85 mm of rain.
How warm is Chicago in September?
Average highs are about 22°C (72°F) and average lows about 17°C (62°F), based on 10 years of daily data.
Does it rain a lot in Chicago in September?
Chicago typically gets around 85 mm of rain in September — some rain.
When is the best time to visit Chicago?
May to June or September to October, avoiding the bitter winter cold and the most humid days of summer.
Figures are long-term averages for the area around Chicago (NASA POWER / ERA5, 2011–2020), not a forecast for a specific year. For upcoming days, see the live multi-source forecast.