September weather forecast
Lake Forest, IL

Weather in September

The first month of the autumn, September, is still a pleasant month in Lake Forest, Illinois, with an average temperature fluctuating between 60.1°F (15.6°C) and 71.2°F (21.8°C).

Temperature

In Lake Forest, the average high-temperature in September marginally drops from a warm 77.5°F (25.3°C) in August to a pleasant 71.2°F (21.8°C). The average low-temperature, in September, is 60.1°F (15.6°C).

Humidity

In September, the average relative humidity in Lake Forest is 75%.

Rainfall

In September, the rain falls for 13.6 days. Throughout September, 2.6" (66mm) of precipitation is accumulated. Throughout the year, there are 154.1 rainfall days, and 30.24" (768mm) of precipitation is accumulated.

Snowfall

May through September are months without snowfall in Lake Forest.

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 7:25 pm. On the last day of September, sunrise is at 6:47 am and sunset at 6:34 pm CDT.

Sunshine

In September, the average sunshine in Lake Forest is 9.2h.

UV index

In September, the average daily maximum UV index in Lake Forest is 4. A UV Index estimate of 3 to 5 represents a medium health hazard from exposure to the Sun's UV radiation for average individuals.
Note: The daily maximum UV index of 4 in September interpret into the following advice:
Take precautions - Protection against sunburn is recommended. The Sun's most intense and consequently most harmful UV radiation during midday hours should be decreased by minimizing exposure and seeking shade. 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 Lake Forest?

The average relative humidity in September in Lake Forest, Illinois, is 75%.

How much does it rain in Lake Forest in September?

In Lake Forest, Illinois, in September, during 13.6 rainfall days, 2.6" (66mm) of precipitation is typically accumulated.

When it does not snow in Lake Forest?

May through September are months without snowfall.

Does it snow in Lake Forest in September?

In Lake Forest, in September, it doesn't snow. In October, it regularly snows.

How many hours of daylight does Lake Forest have in September?

In Lake Forest, the average day length in September is 12h and 28min.

What time are sunrise and sunset in September in Lake Forest?

On the first day of September in Lake Forest, sunrise is at 6:16 am and sunset at 7:25 pm. On the last day of the month, sunrise is at 6:47 am and sunset at 6:34 pm CDT.

How long on average sun shines in September in Lake Forest?

The average sunshine duration in September in Lake Forest, Illinois, is 9.2h.

What is the UV index reading in September in Lake Forest?

In Lake Forest, the average daily maximum UV index in September is 4. A UV Index of 3 to 5 symbolizes a medium hazard to health from exposure to Sun's UV rays.
Average humidity
Average rainfall days
Average snowfall
Average snowfall days
Average sunshine days
Average UV index
Average cloud cover
Average visibility

Average temperature in September
Lake Forest, IL

Average temperature in September - Lake Forest, IL
  • Average high temperature in September: 71.2°F

The warmest month (with the highest average high temperature) is July (77.7°F).
The month with the lowest average high temperature is January (28.6°F).

  • Average low temperature in September: 60.1°F

The months with the highest average low temperature are July and August (66.7°F).
The coldest month (with the lowest average low temperature) is January (18.9°F).

[Resources]

Average pressure in September
Lake Forest, IL

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

The month with the highest atmospheric pressure is January (30.1"Hg).
The month with the lowest atmospheric pressure is June (29.92"Hg).

[Resources]

Average wind speed in September
Lake Forest, IL

Average wind speed in September - Lake Forest, IL
  • Average wind speed in September: 8.9mph

The windiest month (with the highest average wind speed) is January (11.9mph).
The calmest month (with the lowest average wind speed) is August (7.4mph).

[Resources]

Average humidity in September
Lake Forest, IL

Average humidity in September - Lake Forest, IL
  • Average humidity in September: 75%

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

[Resources]

Average rainfall in September
Lake Forest, IL

Average rainfall in September - Lake Forest, IL
  • Average rainfall in September: 2.6"

The wettest months (with the highest rainfall) are May and June (3.82").
The driest month (with the least rainfall) is December (1.3").

[Resources]

Average rainfall days in September
Lake Forest, IL

Average rainfall days in September - Lake Forest, IL
  • Average rainfall days in September: 13.6 days

The month with the highest number of rainy days is May (17.7 days).
The month with the least rainy days is February (5.9 days).

[Resources]

Average snowfall in September
Lake Forest, IL

Average snowfall in September - Lake Forest, IL
  • Average snowfall in September: 0"

The month with the highest snowfall is January (4.13").
The months with the least snowfall are May, June, July, August and September (0").

[Resources]

Average snowfall days in September
Lake Forest, IL

Average snowfall days in September - Lake Forest, IL
  • Average snowfall days in September: 0 days

The month with the highest number of snowfall days is January (11.9 days).
The months with the least snowfall days are May, June, July, August and September (0 days).

[Resources]

Average daylight in September /
Average sunshine in September
Lake Forest, IL

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

The month with the longest days is June (Average daylight: 15h and 13min).
The month with the shortest days is December (Average daylight: 9h and 9min).

  • Average sunshine in September: 9h and 12min

The month with the most sunshine is August (Average sunshine: 10h and 42min).
The month with the least sunshine is January (Average sunshine: 3h and 48min).

[Resources]

Average sunshine days in September
Lake Forest, IL

Average sunshine days in September - Lake Forest, IL
  • Average sunshine days in September: 13.3 days

The month with the most sunshine days is December (15.3 days).
The month with the least sunshine days is April (10.8 days).

[Resources]

Average UV index in September
Lake Forest, IL

Average UV index in September - Lake Forest, IL
  • Average UV index in September: 4

The months with the highest UV index are June, July and August (UV index 6).
The month with the lowest UV index is December (UV index 1).

[Resources]

Average cloud cover in September
Lake Forest, IL

Average cloud cover in September - Lake Forest, IL
  • Average cloud cover in September: 29

The month with the most cloud cover is January (Cloud cover 61).
The months with the least cloud cover are July and August (Cloud cover 27).

[Resources]

Average visibility in September
Lake Forest, IL

Average visibility in September - Lake Forest, 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