September weather forecastIllinois City, IL
September
Weather in September
The first month of the autumn, September, is still a warm month in Illinois City, Illinois, with an average temperature fluctuating between 75.4°F (24.1°C) and 56.3°F (13.5°C).Temperature
As August shifts into September, a minor alteration in temperatures is observed, with average highs reducing from 80.8°F (27.1°C) to a still moderately hot 75.4°F (24.1°C). An average temperature of 56.3°F (13.5°C) is recorded during the nights in September.Humidity
In September, the average relative humidity is 76%.Rainfall
In Illinois City, in September, it is raining for 9.5 days, with typically 1.38" (35mm) of accumulated precipitation. Throughout the year, there are 128 rainfall days, and 19.29" (490mm) of precipitation is accumulated.Snowfall
In Illinois City, snow does not fall in May through September.Daylight
In Illinois City, the average length of the day in September is 12h and 28min.On the first day of September, sunrise is at 6:30 am and sunset at 7:36 pm. On the last day of the month, sunrise is at 7:00 am and sunset at 6:46 pm CDT.
Sunshine
The average sunshine in September is 9.4h.UV index
The average daily maximum UV index in September is 4. A UV Index reading of 3 to 5 represents a medium health hazard from unsafe exposure to UV radiation for the ordinary person.Note: The maximum daily UV index of 4 in September converts into the following recommendations:
Make use of precautions - Shielding skin and eyes from injury is a requirement. UV radiation is strongest from the Sun during midday; protect yourself by staying in shaded areas. A wide-brimmed hat is a shield, deflecting up to 50% of harmful UV radiation from eyes.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
Average temperature in September
Illinois City, IL
- Average high temperature in September: 75.4°F
The warmest month (with the highest average high temperature) is July (81.7°F).
The month with the lowest average high temperature is January (28.2°F).
- Average low temperature in September: 56.3°F
The month with the highest average low temperature is July (65.1°F).
The coldest month (with the lowest average low temperature) is January (16.2°F).
Average pressure in September
Illinois City, IL
- Average pressure in September: 30.02"Hg
The month with the highest atmospheric pressure is January (30.14"Hg).
The month with the lowest atmospheric pressure is June (29.9"Hg).
Average wind speed in September
Illinois City, IL
- Average wind speed in September: 7.8mph
The windiest month (with the highest average wind speed) is April (10.6mph).
The calmest month (with the lowest average wind speed) is August (6.7mph).
Average humidity in September
Illinois City, IL
- Average humidity in September: 76%
The months with the highest relative humidity are January and July (83%).
The month with the lowest relative humidity is October (71%).
Average rainfall in September
Illinois City, IL
- Average rainfall in September: 1.38"
The wettest month (with the highest rainfall) is May (3.31").
The driest month (with the least rainfall) is December (0.75").
Average rainfall days in September
Illinois City, IL
- Average rainfall days in September: 9.5 days
The month with the highest number of rainy days is June (17 days).
The month with the least rainy days is January (4.2 days).
Average snowfall in September
Illinois City, IL
- Average snowfall in September: 0"
The month with the highest snowfall is February (2.52").
The months with the least snowfall are May, June, July, August and September (0").
Average snowfall days in September
Illinois City, IL
- Average snowfall days in September: 0 days
The month with the highest number of snowfall days is January (10.3 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
Illinois City, IL
- Average daylight in September: 12h and 30min
The month with the longest days is June (Average daylight: 15h and 6min).
The month with the shortest days is December (Average daylight: 9h and 12min).
- Average sunshine in September: 9h and 24min
The month with the most sunshine is July (Average sunshine: 10h and 18min).
The month with the least sunshine is January (Average sunshine: 4h and 0min).
Average sunshine days in September
Illinois City, IL
- Average sunshine days in September: 18.5 days
The month with the most sunshine days is November (19.6 days).
The month with the least sunshine days is June (10.8 days).
Average UV index in September
Illinois City, IL
- Average UV index in September: 4
The months with the highest UV index are June and July (UV index 6).
The month with the lowest UV index is January (UV index 1).
Average cloud cover in September
Illinois City, IL
- Average cloud cover in September: 30
The month with the most cloud cover is January (Cloud cover 57).
The month with the least cloud cover is August (Cloud cover 29).
Average visibility in September
Illinois City, 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).
