Contents
- Weather in September
- Frequently asked questions
- Average temperature in September
- Average pressure in September
- Average wind speed in September
- Average humidity in September
- Average rainfall in September
- Average rainfall days in September
- Average snowfall in September
- Average snowfall days in September
- Average daylight in September
- Average sunshine in September
- Average sunshine days in September
- Average UV index in September
- Average cloud cover in September
- Average visibility in September
Weather in September
Temperature
With the onset of September, Lake Forest's climate undergoes a slight change as the average high-temperature moves from a warm 77.5°F (25.3°C) in August to an agreeable 71.2°F (21.8°C). Nighttime temperature in Lake Forest dips to a mean of 60.1°F (15.6°C) during September.Humidity
In September, the average relative humidity in Lake Forest, Illinois, is 75%.Rainfall
In Lake Forest, during September, the rain falls for 13.6 days and regularly aggregates up to 2.6" (66mm) of precipitation. Throughout the year, in Lake Forest, there are 154.1 rainfall days, and 30.24" (768mm) of precipitation is accumulated.Snowfall
May through September are months without snowfall.Daylight
In September, the average length of the day is 12h and 28min.On the first day of September in Lake Forest, sunrise is at 6:17 am and sunset at 7:24 pm. On the last day of the month, sunrise is at 6:48 am and sunset at 6:34 pm CDT.
Sunshine
In Lake Forest, the average sunshine in September is 9.2h.UV index
In September, the average daily maximum UV index is 4. A UV Index value of 3 to 5 symbolizes a moderate threat to health from exposure to the Sun's UV radiation for the ordinary person.Note: The daily high UV index of 4 in September translates into this advice:
Undertake protective steps - Preventing sun damage is advised. It's crucial to reduce time in the direct Sun around mid-day due to the intense solar radiation. Combat UV radiation's detrimental effects with sun-safe clothing and UV-blocking eyewear.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
What is the usual temperature for Lake Forest in September?
What is the average humidity in September in Lake Forest?
How many days does it rain in September in Lake Forest?
When it does not snow in Lake Forest?
Does it snow in Lake Forest in September?
What is the average length of the day in September in Lake Forest?
When is the sunrise / sunset in September in Lake Forest?
How many hours of sunshine does Lake Forest have in September?
How high is the UV index in September in Lake Forest?
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).
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).
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).
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%).
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").
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).
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").
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).
Average daylight in September /
Average sunshine in September
Lake Forest, IL
- Average daylight in September: 12h and 3min
The month with the longest days is June (Average daylight: 15h and 12min).
The month with the shortest days is December (Average daylight: 9h and 12min).
- Average sunshine in September: 9h and 1min
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).
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).
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).
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).
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).
Lake Forest, Illinois, USA
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