September weather forecastRosemont, IL
September
Weather in September
The first month of the autumn, September, is still a warm month in Rosemont, Illinois, with an average temperature ranging between min 59.5°F (15.3°C) and max 73.4°F (23°C).Temperature
The onset of September entails a subtle temperature shift, as the average high-temperature eases from a moderately hot 80.1°F (26.7°C) in August to a still warm 73.4°F (23°C). Rosemont, during the month of September, experiences an average low-temperature of 59.5°F (15.3°C).Humidity
The average relative humidity in September is 74%.Rainfall
In Rosemont, in September, it is raining for 13.5 days, with typically 1.97" (50mm) of accumulated precipitation. In Rosemont, during the entire year, the rain falls for 146.5 days and collects up to 24.13" (613mm) of precipitation.Snowfall
In Rosemont, snow does not fall in June through September.Daylight
The average length of the day in September in Rosemont is 12h and 28min.On the first day of September, 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
The average sunshine in September in Rosemont, Illinois, is 8.8h.UV index
In September, the average daily maximum UV index in Rosemont, Illinois, is 4. A UV Index estimate of 3 to 5 represents a medium vulnerability from exposure to the Sun's UV radiation for ordinary individuals.Note: In September, the maximum UV index of 4 suggests these recommendations:
Proceed with care. Light skin individuals may be exposed to burns in fewer than 30 minutes. The best time to avoid the Sun's harmful UV radiation is during midday when it's most potent. A hat with a broad brim is indispensable, filtering out up to half of UV rays.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
Average temperature in September
Rosemont, IL
- Average high temperature in September: 73.4°F
The warmest month (with the highest average high temperature) is July (81°F).
The month with the lowest average high temperature is January (28.8°F).
- Average low temperature in September: 59.5°F
The month with the highest average low temperature is July (66.7°F).
The coldest month (with the lowest average low temperature) is January (18.1°F).
Average pressure in September
Rosemont, 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
Rosemont, IL
- Average wind speed in September: 7.8mph
The windiest month (with the highest average wind speed) is January (10.6mph).
The calmest month (with the lowest average wind speed) is August (6.6mph).
Average humidity in September
Rosemont, IL
- Average humidity in September: 74%
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
Rosemont, IL
- Average rainfall in September: 1.97"
The wettest month (with the highest rainfall) is May (3.15").
The driest month (with the least rainfall) is December (0.91").
Average rainfall days in September
Rosemont, IL
- Average rainfall days in September: 13.5 days
The month with the highest number of rainy days is July (17.5 days).
The month with the least rainy days is February (5.3 days).
Average snowfall in September
Rosemont, IL
- Average snowfall in September: 0"
The month with the highest snowfall is February (3.39").
The months with the least snowfall are June, July, August and September (0").
Average snowfall days in September
Rosemont, IL
- Average snowfall days in September: 0 days
The month with the highest number of snowfall days is January (11.7 days).
The months with the least snowfall days are June, July, August and September (0 days).
Average daylight in September /
Average sunshine in September
Rosemont, 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 48min
The month with the most sunshine is July (Average sunshine: 10h and 12min).
The month with the least sunshine is January (Average sunshine: 3h and 42min).
Average sunshine days in September
Rosemont, IL
- Average sunshine days in September: 13.2 days
The month with the most sunshine days is November (17.1 days).
The month with the least sunshine days is July (10.3 days).
Average UV index in September
Rosemont, IL
- Average UV index in September: 4
The months with the highest UV index are June, July and August (UV index 6).
The months with the lowest UV index are January and December (UV index 1).
Average cloud cover in September
Rosemont, IL
- Average cloud cover in September: 32
The month with the most cloud cover is January (Cloud cover 62).
The months with the least cloud cover are July and August (Cloud cover 30).
Average visibility in September
Rosemont, 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).
