September weather forecastWillowbrook, IL
September
Weather in September
September, the first month of the autumn in Willowbrook, is still a warm month, with an average temperature varying between 58.6°F (14.8°C) and 74.1°F (23.4°C).Temperature
A modest decline in the average high-temperature is seen during September, decreasing from a moderately hot 80.6°F (27°C) in August to a still warm 74.1°F (23.4°C). Willowbrook's nighttime temperature in September falls to an average of 58.6°F (14.8°C).Humidity
The average relative humidity in September in Willowbrook, Illinois, is 75%.Rainfall
In Willowbrook, during September, the rain falls for 15 days and regularly aggregates up to 2.68" (68mm) of precipitation. In Willowbrook, during the entire year, the rain falls for 166.8 days and collects up to 34.96" (888mm) of precipitation.Snowfall
In Willowbrook, Illinois, snow does not fall in May through September.Daylight
The average length of the day in September is 12h and 28min.On the first day of September in Willowbrook, sunrise is at 6:18 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 Willowbrook, the average sunshine in September is 8.9h.UV index
In Willowbrook, the average daily maximum UV index in September is 4. A UV Index estimate of 3 to 5 represents a moderate health risk from exposure to the Sun's UV radiation for ordinary individuals.Note: The maximum UV index of 4 during September translates into these guidelines:
Ensure safety - Imperative it is to shield skin and eyes from damage. Solar radiation peaks around mid-day, so it's wise to limit exposure to the Sun at this time. For holistic sun protection encompassing the eyes, ears, face, and neck, a wide-brim hat is key.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
Average temperature in September
Willowbrook, IL
- Average high temperature in September: 74.1°F
The warmest month (with the highest average high temperature) is July (81.9°F).
The month with the lowest average high temperature is January (28.9°F).
- Average low temperature in September: 58.6°F
The month with the highest average low temperature is July (66.6°F).
The coldest month (with the lowest average low temperature) is January (18.3°F).
Average pressure in September
Willowbrook, 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
Willowbrook, IL
- Average wind speed in September: 7.4mph
The windiest month (with the highest average wind speed) is January (10.2mph).
The calmest month (with the lowest average wind speed) is August (6.3mph).
Average humidity in September
Willowbrook, 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 (72%).
Average rainfall in September
Willowbrook, IL
- Average rainfall in September: 2.68"
The wettest month (with the highest rainfall) is May (4.61").
The driest months (with the least rainfall) are November and December (1.77").
Average rainfall days in September
Willowbrook, IL
- Average rainfall days in September: 15 days
The month with the highest number of rainy days is June (19.4 days).
The month with the least rainy days is February (5.9 days).
Average snowfall in September
Willowbrook, IL
- Average snowfall in September: 0"
The month with the highest snowfall is February (5.28").
The months with the least snowfall are May, June, July, August and September (0").
Average snowfall days in September
Willowbrook, IL
- Average snowfall days in September: 0 days
The month with the highest number of snowfall days is January (13.3 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
Willowbrook, 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: 8h and 54min
The month with the most sunshine is August (Average sunshine: 10h and 18min).
The month with the least sunshine is January (Average sunshine: 3h and 42min).
Average sunshine days in September
Willowbrook, IL
- Average sunshine days in September: 11.9 days
The month with the most sunshine days is November (16.1 days).
The month with the least sunshine days is June (8.2 days).
Average UV index in September
Willowbrook, IL
- Average UV index in September: 4
The months with the highest UV index are July and August (UV index 6).
The month with the lowest UV index is December (UV index 1).
Average cloud cover in September
Willowbrook, IL
- Average cloud cover in September: 31
The month with the most cloud cover is January (Cloud cover 61).
The month with the least cloud cover is August (Cloud cover 29).
Average visibility in September
Willowbrook, IL
- Average visibility in September: 6mi
The months with the highest visibility are March, April, May, June, July, August, September, October, November and December (6mi).
The months with the lowest visibility are January and February (5mi).
