September weather forecastOak Brook, IL
September
Weather in September
The first month of the autumn, September, is also a moderately hot month in Oak Brook, Illinois, with an average temperature fluctuating between 74.3°F (23.5°C) and 57.9°F (14.4°C).Temperature
As September arrives, Oak Brook's weather displays a minor decrease in high-temperatures, transitioning from August's 81.1°F (27.3°C) to a still moderately hot 74.3°F (23.5°C). Throughout the nights in September, an average low-temperature of 57.9°F (14.4°C) is noted.Humidity
In September, the average relative humidity is 75%.Rainfall
In Oak Brook, in September, it is raining for 11.5 days, with typically 1.18" (30mm) of accumulated precipitation. In Oak Brook, during the entire year, the rain falls for 118.5 days and collects up to 13.74" (349mm) of precipitation.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, 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 Oak Brook, the average sunshine in September is 8.7h.UV index
In Oak Brook, the average daily maximum UV index in September is 4. A UV Index of 3 to 5 symbolizes a moderate health risk from unsafe exposure to UV radiation for the ordinary person.Note: A maximum UV index of 4 in September translates into the following recommendations:
Make use of precautions - Shielding skin and eyes from injury is a requirement. Exposing oneself to the midday Sun can be harmful due to the strong UV radiation; limit your time outside. Consider a wide-brim hat essential for effective sun defense covering your face, neck, and eyes.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
Average temperature in September
Oak Brook, IL
- Average high temperature in September: 74.3°F
The warmest month (with the highest average high temperature) is July (82.4°F).
The month with the lowest average high temperature is January (28.8°F).
- Average low temperature in September: 57.9°F
The month with the highest average low temperature is July (66.4°F).
The coldest month (with the lowest average low temperature) is January (17.1°F).
Average pressure in September
Oak Brook, 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
Oak Brook, IL
- Average wind speed in September: 7mph
The windiest month (with the highest average wind speed) is January (9.7mph).
The calmest month (with the lowest average wind speed) is August (6.1mph).
Average humidity in September
Oak Brook, 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
Oak Brook, IL
- Average rainfall in September: 1.18"
The wettest month (with the highest rainfall) is May (1.97").
The driest month (with the least rainfall) is December (0.63").
Average rainfall days in September
Oak Brook, IL
- Average rainfall days in September: 11.5 days
The month with the highest number of rainy days is May (14.9 days).
The month with the least rainy days is February (4.2 days).
Average snowfall in September
Oak Brook, IL
- Average snowfall in September: 0"
The month with the highest snowfall is February (2.28").
The months with the least snowfall are May, June, July, August and September (0").
Average snowfall days in September
Oak Brook, IL
- Average snowfall days in September: 0 days
The month with the highest number of snowfall days is January (9.7 days).
The months with the least snowfall days are June, July, August and September (0 days).
Average daylight in September /
Average sunshine in September
Oak Brook, 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 42min
The month with the most sunshine is August (Average sunshine: 10h and 0min).
The month with the least sunshine is January (Average sunshine: 3h and 42min).
Average sunshine days in September
Oak Brook, IL
- Average sunshine days in September: 16.1 days
The month with the most sunshine days is December (20.7 days).
The month with the least sunshine days is July (11.8 days).
Average UV index in September
Oak Brook, 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 January (UV index 1).
Average cloud cover in September
Oak Brook, IL
- Average cloud cover in September: 32
The month with the most cloud cover is January (Cloud cover 61).
The month with the least cloud cover is August (Cloud cover 31).
Average visibility in September
Oak Brook, 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).
