Chicago
Illinois, USA
Long term weather forecast
Long term weather forecast

September weather forecast and Climate
Chicago, IL

  • Average high temperature in September: 24.1°C

Warmest month (with highest average high temperature) is July (29°C).
Month with lowest average high temperature is January (-0.3°C).

  • Average low temperature in September: 14.2°C

Month with highest average low temperature is July (19.7°C).
Coldest month (with lowest average low temperature) is January (-7.7°C).

  • Average humidity in September: 71.1%

Month with highest relative humidity is December (75.5%).
Month with lowest relative humidity is May (64.1%).

  • Average rainfall in September: 84.1mm

Wettest month (with highest rainfall) is May (104.9mm).
Driest month (with lowest rainfall) is February (49.3mm).

  • Average rainfall days in September: 8.2 days

Month with highest number of rainy days is May (11.4 days).
Month with lowest number of rainy days is September (8.2 days).

  • Average snowfall in September: 0mm

Month with highest snowfall is January (292.1mm).
Months with lowest snowfall are May, June, July, August and September (0mm).

  • Average snowfall days in September: 0 days

Month with highest number of snowfall days is January (8.1 days).
Months with lowest number of snowfall days are May, June, July, August and September (0 days).

  • Average sea temperature in September: 19°C

Best month for swimming (with highest average sea temperature) is August (21°C).
Coldest months (with lowest average sea temperature) are February, March and April (3°C).

  • Average daylight in September: 12h

Months with longest days are May, June and July (Average daylight: 15h).
Month with shortest days is December (Average daylight: 9h).

  • Average sunshine in September: 7.6h

Month with most sunshine is June (Average sunshine: 10.4h).
Month with least sunshine is December (Average sunshine: 3.4h).

  • Average UV index in September: 6

Months with highest UV index are June and July (UV index 9).
Months with lowest UV index are January and December (UV index 1).

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