September weather forecastFlat Rock, IL
September
Weather in September
The first month of the autumn, September, is still a warm month in Flat Rock, Illinois, with an average temperature ranging between min 59.5°F (15.3°C) and max 77.9°F (25.5°C).Temperature
With the advent of September, Flat Rock experiences an average high-temperature of a still warm 77.9°F (25.5°C), mirroring a close resemblance to the previous month. An average nighttime temperature of 59.5°F (15.3°C) is noted during the month of September.Humidity
In Flat Rock, the average relative humidity in September is 75%.Rainfall
September is the month with the least rainfall. Rain falls for 12.6 days and accumulates 1.89" (48mm) of precipitation.Snowfall
In Flat Rock, snow does not fall in May through October.Daylight
In Flat Rock, the average length of the day in September is 12h and 26min.On the first day of September, sunrise is at 6:20 am and sunset at 7:20 pm. On the last day of the month, sunrise is at 6:46 am and sunset at 6:34 pm CDT.
Sunshine
In September, the average sunshine is 8.9h.UV index
In Flat Rock, the average daily maximum UV index in September is 5. A UV Index reading of 3 to 5 represents a medium health hazard from unprotected exposure to Sun's UV rays for average individuals.Note: In September, a daily UV index of 5 turns into the following recommendations:
Undertake protective steps - Preventing sun damage is advised. The mid-day Sun emits the most powerful UV radiation, so seek shade and minimize exposure. Sun-related eye harm can be minimized with proper sunglasses offering UVA and UVB coverage.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
Average temperature in September
Flat Rock, 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 (36.1°F).
- Average low temperature in September: 59.5°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 (23.4°F).
Average pressure in September
Flat Rock, 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
Flat Rock, IL
- Average wind speed in September: 6.7mph
The windiest months (with the highest average wind speed) are January and February (10mph).
The calmest months (with the lowest average wind speed) are July and August (5.9mph).
Average humidity in September
Flat Rock, IL
- Average humidity in September: 75%
The month with the highest relative humidity is July (81%).
The month with the lowest relative humidity is October (71%).
Average rainfall in September
Flat Rock, IL
- Average rainfall in September: 1.89"
The wettest month (with the highest rainfall) is April (5.2").
The driest month (with the least rainfall) is September (1.89").
Average rainfall days in September
Flat Rock, IL
- Average rainfall days in September: 12.6 days
The month with the highest number of rainy days is May (19.8 days).
The month with the least rainy days is January (8.4 days).
Average snowfall in September
Flat Rock, IL
- Average snowfall in September: 0"
The month with the highest snowfall is January (2.32").
The months with the least snowfall are May, June, July, August, September and October (0").
Average snowfall days in September
Flat Rock, IL
- Average snowfall days in September: 0 days
The month with the highest number of snowfall days is January (6.8 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
Flat Rock, 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: 8h and 54min
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 12min).
Average sunshine days in September
Flat Rock, IL
- Average sunshine days in September: 15.1 days
The month with the most sunshine days is November (18 days).
The month with the least sunshine days is May (9.7 days).
Average UV index in September
Flat Rock, 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
Flat Rock, IL
- Average cloud cover in September: 31
The month with the most cloud cover is January (Cloud cover 55).
The month with the least cloud cover is August (Cloud cover 29).
Average visibility in September
Flat Rock, 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).
