September weather forecast
Chicago, IL

The city of Chicago in Illinois on the shores of Lake Michigan, with a superb view of the sandy beach of Oak Street
The city of Chicago in Illinois on the shores of Lake Michigan, with a superb view of the sandy beach of Oak Street

Weather in September

The first month of the autumn, September, is also an agreeable month in Chicago, Illinois, with temperature in the range of an average low of 61.2°F (16.2°C) and an average high of 71.1°F (21.7°C).

Temperature

In Chicago, Illinois, the average high-temperature in September slightly decreases from a moderately hot 77.5°F (25.3°C) in August to an agreeable 71.1°F (21.7°C). In September, the average low-temperature is 61.2°F (16.2°C).

Humidity

The average relative humidity in September is 75%.

Rainfall

In Chicago, it is raining for 14.5 days, with typically 3.23" (82mm) of accumulated precipitation. In Chicago, during the entire year, the rain falls for 160.2 days and collects up to 36.97" (939mm) of precipitation.

Snowfall

June through October are months without snowfall.

Ocean temperature

In Chicago, the average seawater temperature in September is 68.5°F (20.3°C).
Note: Swimming in 68.5°F (20.3°C) is not enjoyable for the majority. Controlling breathing becomes progressively more difficult as surface water temperature decreases below 69.8°F (21°C).

Daylight

The average length of the day in September is 12h and 28min.
On the first day of the month, sunrise is at 6:16 am and sunset at 7:24 pm. On the last day of September, in Chicago, sunrise is at 6:46 am and sunset at 6:34 pm CDT.

Sunshine

The average sunshine in September is 9.1h.

UV index

In September, the average daily maximum UV index in Chicago is 4. A UV Index estimate of 3 to 5 represents a medium health hazard from unprotected exposure to Sun's UV rays for the ordinary person.
Note: In September, the average maximum UV index of 4 translate into the following recommendations:
Take precautions - Protection against sun damage is advised. The solar radiation is most powerful near the mid-day, so the exposure to the direct Sun should be reduced accordingly. On bright days sunglasses that block both UVA and UVB rays should be worn. A hat with a wide brim is extremely helpful, as it can prevent roughly 50% of UV radiation from reaching the eyes.
[Resources]

FAQ

What is the average humidity in September in Chicago?

In September, the average relative humidity in Chicago, Illinois, is 75%.

How much does it rain in Chicago in September?

In Chicago, in September, it is raining for 14.5 days, with typically 3.23" (82mm) of accumulated precipitation.

When it does not snow in Chicago?

In Chicago, Illinois, snow does not fall in June through October.

What is the ocean temperature in September in Chicago?

In Chicago, Illinois, the average seawater temperature in September is 68.5°F (20.3°C). For swimming, a surface water temperature of 68.5°F (20.3°C) is not enjoyable for the majority. It is not considered safe, as controlling breathing becomes progressively more difficult as water temperature decreases below 69.8°F (21°C).

What is the average length of the day in September in Chicago?

The average day length in September is 12h and 28min.

What time are sunrise and sunset in September in Chicago?

On the first day of September, sunrise is at 6:16 am and sunset at 7:24 pm. On the last day of the month, sunrise is at 6:46 am and sunset at 6:34 pm CDT.

How many hours of sunshine does Chicago have in September?

The average sunshine duration in September is 9.1h.

What is the UV index intensity in September in Chicago?

In September, the average daily maximum UV index is 4. A UV Index value of 3 to 5 symbolizes a moderate vulnerability from unsafe exposure to Sun's UV rays.
Average humidity
Average rainfall days
Average snowfall
Average snowfall days
Average sunshine
Average sunshine days
Average UV index
Average cloud cover
Average visibility

Average temperature in September
Chicago, IL

Average temperature in September - Chicago, IL
  • Average high temperature in September: 71.1°F

The warmest month (with the highest average high temperature) is August (77.5°F).
The month with the lowest average high temperature is January (29.7°F).

  • Average low temperature in September: 61.2°F

The month with the highest average low temperature is July (67.8°F).
The coldest month (with the lowest average low temperature) is January (20.7°F).

[Resources]

Average pressure in September
Chicago, IL

Average pressure in September - Chicago, IL
  • Average pressure in September: 30.03"Hg

The month with the highest atmospheric pressure is January (30.11"Hg).
The month with the lowest atmospheric pressure is June (29.92"Hg).

[Resources]

Average wind speed in September
Chicago, IL

Average wind speed in September - Chicago, IL
  • Average wind speed in September: 9.3mph

The windiest month (with the highest average wind speed) is January (12.5mph).
The calmest month (with the lowest average wind speed) is July (7.7mph).

[Resources]

Average humidity in September
Chicago, IL

Average humidity in September - Chicago, IL
  • Average humidity in September: 75%

The month with the highest relative humidity is January (82%).
The month with the lowest relative humidity is October (73%).

[Resources]

Average rainfall in September
Chicago, IL

Average rainfall in September - Chicago, IL
  • Average rainfall in September: 3.23"

The wettest month (with the highest rainfall) is June (4.88").
The driest month (with the least rainfall) is December (1.65").

[Resources]

Average rainfall days in September
Chicago, IL

Average rainfall days in September - Chicago, IL
  • Average rainfall days in September: 14.5 days

The month with the highest number of rainy days is July (18.5 days).
The month with the least rainy days is February (5.5 days).

[Resources]

Average snowfall in September
Chicago, IL

Average snowfall in September - Chicago, IL
  • Average snowfall in September: 0"

The month with the highest snowfall is February (3.54").
The months with the least snowfall are June, July, August, September and October (0").

[Resources]

Average snowfall days in September
Chicago, IL

Average snowfall days in September - Chicago, IL
  • Average snowfall days in September: 0 days

The month with the highest number of snowfall days is January (10.6 days).
The months with the least snowfall days are June, July, August and September (0 days).

[Resources]

Average sea temperature in September
Chicago, IL

Average sea temperature in September - Chicago, IL
  • Average sea temperature in September: 68.6°F

The best month for swimming (with the highest average sea temperature) is August (73.9°F).
The coldest month (with the lowest average sea temperature) is February (36.9°F).

[Resources]

Average daylight in September /
Average sunshine in September
Chicago, IL

Average daylight in September / Average sunshine in September - Chicago, IL
  • Average daylight in September: 12h and 28min

The month with the longest days is June (Average daylight: 15h and 11min).
The month with the shortest days is December (Average daylight: 9h and 11min).

  • Average sunshine in September: 9h and 6min

The months with the most sunshine are July and August (Average sunshine: 10h and 36min).
The month with the least sunshine is January (Average sunshine: 3h and 42min).

[Resources]

Average sunshine days in September
Chicago, IL

Average sunshine days in September - Chicago, IL
  • Average sunshine days in September: 12.1 days

The month with the most sunshine days is December (15.5 days).
The month with the least sunshine days is July (9.3 days).

[Resources]

Average UV index in September
Chicago, IL

Average UV index in September - Chicago, IL
  • Average UV index in September: 4

The months with the highest UV index are July and August (UV index 6).
The months with the lowest UV index are January and December (UV index 1).

[Resources]

Average cloud cover in September
Chicago, IL

Average cloud cover in September - Chicago, IL
  • Average cloud cover in September: 30

The month with the most cloud cover is January (Cloud cover 62).
The months with the least cloud cover are July and August (Cloud cover 27).

[Resources]

Average visibility in September
Chicago, IL

Average visibility in September - Chicago, IL
  • Average visibility in September: 6mi

The months with the highest visibility are January, February, March, April, May, June, July, August, September, October, November and December (6mi).
The months with the lowest visibility are January, February, March, April, May, June, July, August, September, October, November and December (6mi).

[Resources]

Weather forecast for your location

1. Click Locate me button
2. Allow the app to use your location
* you will be automatically redirected to the weather forecast for your location