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 introduction of September notes a subtle temperature variation to a still warm 77.2°F (25.1°C) from August's 81.5°F (27.5°C). During September, the nighttime temperature averages to a refreshing 58.5°F (14.7°C).Humidity
The average relative humidity in September is 75%.Rainfall
In Sullivan, in September, it is raining for 10.6 days, with typically 1.06" (27mm) of accumulated precipitation. In Sullivan, during the entire year, the rain falls for 130.9 days and collects up to 15.43" (392mm) of precipitation.Snowfall
In Sullivan, snow does not fall in May through October.Daylight
In September, the average length of the day in Sullivan is 12h and 26min.On the first day of the month, sunrise is at 6:23 am and sunset at 7:25 pm. On the last day of September, sunrise is at 6:50 am and sunset at 6:37 pm CDT.
Sunshine
In Sullivan, the average sunshine in September is 9h.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 unprotected exposure to Sun's UV rays for the ordinary person.Note: In September, the maximum UV index of 5 suggests these recommendations:
Exercise prudence. Persons with fair skin could be burned in under 30 minutes. Minimize direct exposure to the Sun during midday when its radiation is at its peak. Employ a wide-brim hat for potent defense against up to 50% of UV rays.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
What is the average September temperature in Sullivan?
What is the average humidity in September in Sullivan?
How many days does it rain in September in Sullivan?
When it does not snow in Sullivan?
What is the average length of the day in September in Sullivan?
When are sunrise and sunset in September in Sullivan?
How many hours of sunshine does Sullivan have in September?
What is the UV index intensity in September in Sullivan?
Average temperature in September
Sullivan, IL
- Average high temperature in September: 77.2°F
The warmest month (with the highest average high temperature) is July (82.2°F).
The month with the lowest average high temperature is January (33.6°F).
- Average low temperature in September: 58.5°F
The month with the highest average low temperature is July (65.8°F).
The coldest month (with the lowest average low temperature) is January (21.6°F).
Average pressure in September
Sullivan, 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 (29.93"Hg).
Average wind speed in September
Sullivan, IL
- Average wind speed in September: 7.1mph
The windiest month (with the highest average wind speed) is January (10.7mph).
The calmest months (with the lowest average wind speed) are July and August (6.3mph).
Average humidity in September
Sullivan, IL
- Average humidity in September: 75%
The month with the highest relative humidity is July (84%).
The month with the lowest relative humidity is October (70%).
Average rainfall in September
Sullivan, IL
- Average rainfall in September: 1.06"
The wettest month (with the highest rainfall) is June (1.85").
The driest month (with the least rainfall) is February (0.71").
Average rainfall days in September
Sullivan, IL
- Average rainfall days in September: 10.6 days
The month with the highest number of rainy days is May (16.3 days).
The month with the least rainy days is February (5.9 days).
Average snowfall in September
Sullivan, IL
- Average snowfall in September: 0"
The month with the highest snowfall is January (1.54").
The months with the least snowfall are May, June, July, August, September and October (0").
Average snowfall days in September
Sullivan, IL
- Average snowfall days in September: 0 days
The month with the highest number of snowfall days is January (6.4 days).
The months with the least snowfall days are May, June, July, August, September and October (0 days).
Average daylight in September /
Average sunshine in September
Sullivan, IL
- Average daylight in September: 12h and 2min
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 24min).
- Average sunshine in September: 9h and 0min
The month with the most sunshine is June (Average sunshine: 10h and 24min).
The month with the least sunshine is January (Average sunshine: 4h and 6min).
Average sunshine days in September
Sullivan, IL
- Average sunshine days in September: 18.2 days
The month with the most sunshine days is October (20.5 days).
The month with the least sunshine days is May (12.3 days).
Average UV index in September
Sullivan, 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
Sullivan, IL
- Average cloud cover in September: 31
The month with the most cloud cover is January (Cloud cover 56).
The month with the least cloud cover is June (Cloud cover 30).
Average visibility in September
Sullivan, 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).
Sullivan, Illinois, USA
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