Contents
- Weather in September
- Frequently asked questions
- Average temperature in September
- Average pressure in September
- Average wind speed in September
- Average humidity in September
- Average rainfall in September
- Average rainfall days in September
- Average snowfall in September
- Average snowfall days in September
- Average daylight in September
- Average sunshine in September
- Average sunshine days in September
- Average UV index in September
- Average cloud cover in September
- Average visibility in September
Weather in September
Temperature
The start of September comes with a small reduction in the average high-temperature, subtly receding from 85.8°F (29.9°C) in August to a still moderately hot 79.9°F (26.6°C). Chester observes an average low-temperature of 60.1°F (15.6°C) during September nights.Humidity
The average relative humidity in September is 74%.Rainfall
September is the month with the least rainfall. Rain falls for 13 days and accumulates 1.97" (50mm) of precipitation.Snowfall
In Chester, snow does not fall in May through September.Daylight
The average length of the day in September is 12h and 25min.On the first day of September, sunrise is at 6:29 am and sunset at 7:28 pm. On the last day of the month, sunrise is at 6:54 am and sunset at 6:43 pm CDT.
Sunshine
In Chester, the average sunshine in September is 9.3h.UV index
In Chester, the average daily maximum UV index in September is 5. A UV Index reading of 3 to 5 represents a moderate threat to health from exposure to the Sun's UV rays for the average person.Note: A daily maximum UV index of 5 in September translates into the following instructions:
Prioritize safety - Recommendations to avert sunburn are shared. Considering the strength of solar radiation at midday, one should avoid direct Sun exposure. For excellent sun protection for the eyes, ears, face, and neck, consider a wide-brim hat.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
What is the temperature in September?
What is the average humidity in September?
What is the driest month?
How much does it rain in September?
When it does not snow?
Does it snow in September?
What is the average length of the day in September?
What time are sunrise and sunset in September?
How many hours of sunshine does Chester have in September?
What is the UV index intensity in September?
Average temperature in September
Chester, IL
- Average high temperature in September: 79.9°F
The warmest month (with the highest average high temperature) is July (87.4°F).
The month with the lowest average high temperature is January (39.6°F).
- Average low temperature in September: 60.1°F
The month with the highest average low temperature is July (68.5°F).
The coldest month (with the lowest average low temperature) is January (25.7°F).
Average pressure in September
Chester, IL
- Average pressure in September: 30.02"Hg
The month with the highest atmospheric pressure is January (30.16"Hg).
The month with the lowest atmospheric pressure is June (29.93"Hg).
Average wind speed in September
Chester, IL
- Average wind speed in September: 6mph
The windiest month (with the highest average wind speed) is January (9.4mph).
The calmest month (with the lowest average wind speed) is August (5.5mph).
Average humidity in September
Chester, IL
- Average humidity in September: 74%
The month with the highest relative humidity is May (79%).
The month with the lowest relative humidity is October (71%).
Average rainfall in September
Chester, IL
- Average rainfall in September: 1.97"
The wettest month (with the highest rainfall) is April (4.13").
The driest month (with the least rainfall) is September (1.97").
Average rainfall days in September
Chester, IL
- Average rainfall days in September: 13 days
The month with the highest number of rainy days is July (17.8 days).
The month with the least rainy days is January (7.9 days).
Average snowfall in September
Chester, IL
- Average snowfall in September: 0"
The month with the highest snowfall is February (2.56").
The months with the least snowfall are May, June, July, August and September (0").
Average snowfall days in September
Chester, IL
- Average snowfall days in September: 0 days
The month with the highest number of snowfall days is February (5.2 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
Chester, IL
- Average daylight in September: 12h and 2min
The month with the longest days is June (Average daylight: 14h and 48min).
The month with the shortest days is December (Average daylight: 9h and 36min).
- Average sunshine in September: 9h and 2min
The months with the most sunshine are June and July (Average sunshine: 10h and 30min).
The month with the least sunshine is January (Average sunshine: 4h and 42min).
Average sunshine days in September
Chester, IL
- Average sunshine days in September: 15.4 days
The month with the most sunshine days is October (18.9 days).
The month with the least sunshine days is July (9.8 days).
Average UV index in September
Chester, IL
- Average UV index in September: 5
The months with the highest UV index are May, June, July and August (UV index 6).
The months with the lowest UV index are January, February and December (UV index 2).
Average cloud cover in September
Chester, IL
- Average cloud cover in September: 29
The months with the most cloud cover are January and February (Cloud cover 48).
The month with the least cloud cover is June (Cloud cover 27).
Average visibility in September
Chester, 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).
Chester, Illinois, USA
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