Weather in Chicago in September
September in Chicago is mild with average temperatures around 19.2°C (66.6°F). Moderate rainfall of 86mm spread over 10 days.
Data Note: Temperature values are 2001–2020 satellite/reanalysis grid averages from NASA POWER and may differ from airport station normals by a few degrees.
Temperature
High
21.9°C
71.4°F
Low
16.4°C
61.5°F
Precipitation
86 mm
3.4 inches
~10 rainy days
Conditions
Humidity
76%
Comparison to Adjacent Months
September is 3.4°C cooler than August.
September is 6.8°C warmer than October.