September weather forecastChesterfield, IL
September
Weather in September
The first month of the autumn, September, is still a warm month in Chesterfield, Illinois, with an average temperature fluctuating between 77.9°F (25.5°C) and 59.4°F (15.2°C).Temperature
Chesterfield's shift from August to September is accompanied by an average high-temperature of a still warm 77.9°F (25.5°C), a slight deviation from 82.6°F (28.1°C). During September, Chesterfield witnesses a consistent average low-temperature of 59.4°F (15.2°C).Humidity
The average relative humidity in September is 75%.Rainfall
In Chesterfield, in September, during 11.5 rainfall days, 1.73" (44mm) of precipitation is typically accumulated. In Chesterfield, during the entire year, the rain falls for 138.2 days and collects up to 23.31" (592mm) of precipitation.Snowfall
In Chesterfield, snow does not fall in April through October.Daylight
In Chesterfield, the average length of the day in September is 12h and 26min.On the first day of September, sunrise is at 6:29 am and sunset at 7:30 pm. On the last day of the month, sunrise is at 6:56 am and sunset at 6:43 pm CDT.
Sunshine
In Chesterfield, the average sunshine in September is 9.4h.UV index
The average daily maximum UV index in September is 5. A UV Index estimate of 3 to 5 represents a medium vulnerability from unsafe exposure to UV radiation for average individuals.Note: The maximum daily UV index of 5 in September converts into the following recommendations:
Guard yourself - Avoiding sunburn is suggested. Considering the strength of solar radiation at midday, one should avoid direct Sun exposure. For optimum UV protection, wear sun-resistant attire complemented with a hat and quality shades.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
Average temperature in September
Chesterfield, IL
- Average high temperature in September: 77.9°F
The warmest month (with the highest average high temperature) is July (83.8°F).
The month with the lowest average high temperature is January (34.9°F).
- Average low temperature in September: 59.4°F
The month with the highest average low temperature is July (66.9°F).
The coldest month (with the lowest average low temperature) is January (22.5°F).
Average pressure in September
Chesterfield, IL
- Average pressure in September: 30.02"Hg
The month with the highest atmospheric pressure is January (30.15"Hg).
The month with the lowest atmospheric pressure is June (29.92"Hg).
Average wind speed in September
Chesterfield, IL
- Average wind speed in September: 6.6mph
The windiest month (with the highest average wind speed) is January (10.1mph).
The calmest month (with the lowest average wind speed) is July (5.8mph).
Average humidity in September
Chesterfield, IL
- Average humidity in September: 75%
The month with the highest relative humidity is July (82%).
The month with the lowest relative humidity is October (71%).
Average rainfall in September
Chesterfield, IL
- Average rainfall in September: 1.73"
The wettest month (with the highest rainfall) is June (3.07").
The driest months (with the least rainfall) are January and February (1.22").
Average rainfall days in September
Chesterfield, IL
- Average rainfall days in September: 11.5 days
The month with the highest number of rainy days is May (17.3 days).
The month with the least rainy days is January (6.3 days).
Average snowfall in September
Chesterfield, IL
- Average snowfall in September: 0"
The month with the highest snowfall is February (2.28").
The months with the least snowfall are April, May, June, July, August, September and October (0").
Average snowfall days in September
Chesterfield, IL
- Average snowfall days in September: 0 days
The month with the highest number of snowfall days is February (6.3 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
Chesterfield, IL
- Average daylight in September: 12h and 24min
The month with the longest days is June (Average daylight: 14h and 54min).
The month with the shortest days is December (Average daylight: 9h and 30min).
- Average sunshine in September: 9h and 24min
The month with the most sunshine is June (Average sunshine: 10h and 18min).
The month with the least sunshine is January (Average sunshine: 4h and 24min).
Average sunshine days in September
Chesterfield, IL
- Average sunshine days in September: 16 days
The month with the most sunshine days is October (19.8 days).
The month with the least sunshine days is May (11.1 days).
Average UV index in September
Chesterfield, IL
- Average UV index in September: 5
The months with the highest UV index are June, July and August (UV index 6).
The months with the lowest UV index are January, February, November and December (UV index 2).
Average cloud cover in September
Chesterfield, IL
- Average cloud cover in September: 29
The month with the most cloud cover is January (Cloud cover 53).
The months with the least cloud cover are August and September (Cloud cover 29).
Average visibility in September
Chesterfield, 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).
