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
Illiopolis marks the onset of September with an average high-temperature of a still moderately hot 77°F (25°C), a subtle shift from August's 81.3°F (27.4°C). Illiopolis, in September, observes a steady average low-temperature of 58.5°F (14.7°C).Humidity
The average relative humidity in September in Illiopolis is 76%.Rainfall
In Illiopolis, in September, during 11.8 rainfall days, 1.81" (46mm) of precipitation is typically accumulated. In Illiopolis, during the entire year, the rain falls for 141.8 days and collects up to 22.24" (565mm) of precipitation.Snowfall
In Illiopolis, snow does not fall in May through October.Daylight
In September, the average length of the day in Illiopolis is 12h and 26min.On the first day of September, sunrise is at 6:25 am and sunset at 7:27 pm. On the last day of the month, sunrise is at 6:52 am and sunset at 6:40 pm CDT.
Sunshine
In September, the average sunshine in Illiopolis is 9h.UV index
In Illiopolis, Illinois, the average daily maximum UV index in September is 5. A UV Index reading of 3 to 5 represents a moderate health risk from exposure to the Sun's UV rays for average individuals.Note: The maximum UV index of 5 during September translates into these guidelines:
Be vigilant - Preventing sunburn is recommended. The midday Sun can be harmful due to its potent UV radiation; seek shade and reduce exposure. Sunglasses that ward off UVA and UVB rays play a pivotal role in reducing solar eye damage. Take heed! Reflection from the snow can almost amplify the Sun's UV radiation by double.
Frequently asked questions
What are September temperatures in Illiopolis?
What is the average humidity in September in Illiopolis?
How many days does it rain in September in Illiopolis?
When it does not snow in Illiopolis?
What is the average length of the day in September in Illiopolis?
When is the sunrise / sunset in September in Illiopolis?
How many hours of sunshine does Illiopolis have in September?
What is the UV index reading in September in Illiopolis?
Average temperature in September
Illiopolis, IL
- Average high temperature in September: 77°F
The warmest month (with the highest average high temperature) is July (82°F).
The month with the lowest average high temperature is January (32.5°F).
- Average low temperature in September: 58.5°F
The month with the highest average low temperature is July (65.7°F).
The coldest month (with the lowest average low temperature) is January (20.5°F).
Average pressure in September
Illiopolis, IL
- Average pressure in September: 30.03"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
Illiopolis, IL
- Average wind speed in September: 7.3mph
The windiest month (with the highest average wind speed) is April (10.6mph).
The calmest months (with the lowest average wind speed) are July and August (6.3mph).
Average humidity in September
Illiopolis, IL
- Average humidity in September: 76%
The month with the highest relative humidity is July (84%).
The month with the lowest relative humidity is October (70%).
Average rainfall in September
Illiopolis, IL
- Average rainfall in September: 1.81"
The wettest month (with the highest rainfall) is May (2.68").
The driest month (with the least rainfall) is December (1.1").
Average rainfall days in September
Illiopolis, IL
- Average rainfall days in September: 11.8 days
The month with the highest number of rainy days is May (17 days).
The months with the least rainy days are January and February (6.3 days).
Average snowfall in September
Illiopolis, IL
- Average snowfall in September: 0"
The month with the highest snowfall is January (2.24").
The months with the least snowfall are May, June, July, August, September and October (0").
Average snowfall days in September
Illiopolis, IL
- Average snowfall days in September: 0.1 days
The month with the highest number of snowfall days is January (9.4 days).
The months with the least snowfall days are May, June, July and August (0 days).
Average daylight in September /
Average sunshine in September
Illiopolis, IL
- Average daylight in September: 12h and 2min
The month with the longest days is June (Average daylight: 15h and 0min).
The month with the shortest days is December (Average daylight: 9h and 24min).
- Average sunshine in September: 9h and 0min
The month with the most sunshine is June (Average sunshine: 10h and 12min).
The month with the least sunshine is January (Average sunshine: 4h and 0min).
Average sunshine days in September
Illiopolis, IL
- Average sunshine days in September: 15.8 days
The month with the most sunshine days is November (18.9 days).
The month with the least sunshine days is May (10.8 days).
Average UV index in September
Illiopolis, IL
- Average UV index in September: 5
The months with the highest UV index are June, July and August (UV index 6).
The month with the lowest UV index is January (UV index 1).
Average cloud cover in September
Illiopolis, IL
- Average cloud cover in September: 31
The month with the most cloud cover is January (Cloud cover 57).
The months with the least cloud cover are June and September (Cloud cover 31).
Average visibility in September
Illiopolis, IL
- Average visibility in September: 6mi
The months with the highest visibility are January, February, March, April, May, June, September, October, November and December (6mi).
The months with the lowest visibility are July and August (5mi).
Illiopolis, Illinois, USA
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