September weather forecastWinnetka, IL
September
Weather in September
The first month of the autumn, September, is still a pleasant month in Winnetka, Illinois, with an average temperature fluctuating between 71.6°F (22°C) and 60.3°F (15.7°C).Temperature
September sees a slight reduction in average high-temperature, with a shift from a warm 78.1°F (25.6°C) in August to a pleasant 71.6°F (22°C). Throughout September, the temperature falls to an average low of 60.3°F (15.7°C).Humidity
In Winnetka, the average relative humidity in September is 74%.Rainfall
In Winnetka, in September, it is raining for 14.8 days, with typically 2.87" (73mm) of accumulated precipitation. Throughout the year, there are 164.7 rainfall days, and 35.28" (896mm) of precipitation is accumulated.Snowfall
In Winnetka, snow does not fall in June through September.Daylight
In Winnetka, the average length of the day in September is 12h and 28min.On the first day of the month, sunrise is at 6:17 am and sunset at 7:24 pm. On the last day of September, sunrise is at 6:47 am and sunset at 6:33 pm CDT.
Sunshine
The average sunshine in September is 9h.UV index
In Winnetka, the average daily maximum UV index in September is 4. A UV Index of 3 to 5 symbolizes a medium health hazard from exposure to the Sun's UV rays for ordinary individuals.Note: A maximum daily UV index of 4 during September morphs into the following directions:
Guard yourself - An obligation to protect skin and eyes from harm exists. The Sun's most harmful UV rays are emitted around midday; avoid staying outdoors for long during this time. Sun protection is enhanced with clothing that boasts a tight weave yet offers a loose fit.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
Average temperature in September
Winnetka, IL
- Average high temperature in September: 71.6°F
The warmest month (with the highest average high temperature) is July (79.2°F).
The month with the lowest average high temperature is January (28.8°F).
- Average low temperature in September: 60.3°F
The month with the highest average low temperature is July (67.1°F).
The coldest month (with the lowest average low temperature) is January (18.9°F).
Average pressure in September
Winnetka, 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).
Average wind speed in September
Winnetka, IL
- Average wind speed in September: 8.6mph
The windiest month (with the highest average wind speed) is January (11.5mph).
The calmest month (with the lowest average wind speed) is August (7.1mph).
Average humidity in September
Winnetka, IL
- Average humidity in September: 74%
The month with the highest relative humidity is January (82%).
The month with the lowest relative humidity is October (73%).
Average rainfall in September
Winnetka, IL
- Average rainfall in September: 2.87"
The wettest months (with the highest rainfall) are May and June (4.57").
The driest month (with the least rainfall) is December (1.65").
Average rainfall days in September
Winnetka, IL
- Average rainfall days in September: 14.8 days
The month with the highest number of rainy days is May (19.1 days).
The month with the least rainy days is February (6.1 days).
Average snowfall in September
Winnetka, IL
- Average snowfall in September: 0"
The month with the highest snowfall is January (4.84").
The months with the least snowfall are June, July, August and September (0").
Average snowfall days in September
Winnetka, IL
- Average snowfall days in September: 0 days
The month with the highest number of snowfall days is January (13.1 days).
The months with the least snowfall days are June, July, August and September (0 days).
Average daylight in September /
Average sunshine in September
Winnetka, IL
- Average daylight in September: 12h and 30min
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 0min
The months with the most sunshine are July and August (Average sunshine: 10h and 24min).
The month with the least sunshine is January (Average sunshine: 3h and 42min).
Average sunshine days in September
Winnetka, IL
- Average sunshine days in September: 11.7 days
The month with the most sunshine days is November (15.5 days).
The month with the least sunshine days is June (9.2 days).
Average UV index in September
Winnetka, 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
Winnetka, IL
- Average cloud cover in September: 30
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 28).
Average visibility in September
Winnetka, 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).
