September weather forecastSaint Charles, IL
September
Weather in September
The first month of the autumn, September, is still a warm month in Saint Charles, Illinois, with an average temperature varying between 73.4°F (23°C) and 56.5°F (13.6°C).Temperature
The shift from August to September includes a minor decrease in the average high-temperature, lightly dropping from a moderately hot 79.5°F (26.4°C) to a still warm 73.4°F (23°C). Saint Charles observes an average nighttime low-temperature of 56.5°F (13.6°C) during the month of September.Humidity
In Saint Charles, the average relative humidity in September is 78%.Rainfall
In Saint Charles, Illinois, during September, the rain falls for 9.5 days and regularly aggregates up to 0.71" (18mm) of precipitation. In Saint Charles, Illinois, during the entire year, the rain falls for 101.9 days and collects up to 8.58" (218mm) of precipitation.Snowfall
In Saint Charles, snow does not fall in May through September.Daylight
In September, the average length of the day in Saint Charles is 12h and 28min.On the first day of the month, sunrise is at 6:19 am and sunset at 7:26 pm. On the last day of September, in Saint Charles, sunrise is at 6:49 am and sunset at 6:36 pm CDT.
Sunshine
In Saint Charles, the average sunshine in September is 8.8h.UV index
The average daily maximum UV index in September is 4. A UV Index estimate of 3 to 5 represents a medium health hazard from exposure to the Sun's UV rays for average individuals.Note: In September, a regular UV index of 4 translates into these guidelines:
Take necessary precautions - Defending against sun damage is advocated. Avoiding direct sun during mid-day hours can prevent harmful UV radiation exposure. To best shield against UV radiation, choose sun-safe garments and dependable sunglasses.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
Average temperature in September
Saint Charles, 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 (27.9°F).
- Average low temperature in September: 56.5°F
The month with the highest average low temperature is July (64.2°F).
The coldest month (with the lowest average low temperature) is January (16.2°F).
Average pressure in September
Saint Charles, 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
Saint Charles, IL
- Average wind speed in September: 7.1mph
The windiest month (with the highest average wind speed) is January (9.9mph).
The calmest month (with the lowest average wind speed) is August (6.1mph).
Average humidity in September
Saint Charles, IL
- Average humidity in September: 78%
The months with the highest relative humidity are January and February (83%).
The month with the lowest relative humidity is October (74%).
Average rainfall in September
Saint Charles, IL
- Average rainfall in September: 0.71"
The wettest month (with the highest rainfall) is May (1.26").
The driest months (with the least rainfall) are November and December (0.39").
Average rainfall days in September
Saint Charles, IL
- Average rainfall days in September: 9.5 days
The month with the highest number of rainy days is May (12.4 days).
The month with the least rainy days is January (3.4 days).
Average snowfall in September
Saint Charles, IL
- Average snowfall in September: 0"
The month with the highest snowfall is January (1.14").
The months with the least snowfall are May, June, July, August and September (0").
Average snowfall days in September
Saint Charles, IL
- Average snowfall days in September: 0 days
The month with the highest number of snowfall days is January (7.6 days).
The months with the least snowfall days are June, July, August and September (0 days).
Average daylight in September /
Average sunshine in September
Saint Charles, 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: 9h and 54min).
The month with the least sunshine is January (Average sunshine: 3h and 42min).
Average sunshine days in September
Saint Charles, IL
- Average sunshine days in September: 17.7 days
The month with the most sunshine days is December (22.4 days).
The month with the least sunshine days is June (13.3 days).
Average UV index in September
Saint Charles, 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
Saint Charles, IL
- Average cloud cover in September: 32
The month with the most cloud cover is January (Cloud cover 62).
The month with the least cloud cover is September (Cloud cover 32).
Average visibility in September
Saint Charles, IL
- Average visibility in September: 6mi
The months with the highest visibility are January, February, March, April, May, June, August, September, October, November and December (6mi).
The month with the lowest visibility is July (5mi).
