September weather forecastPotomac, IL
September
Weather in September
September, the first month of the autumn in Potomac, is also a moderately hot month, with an average temperature ranging between min 57.6°F (14.2°C) and max 75.6°F (24.2°C).Temperature
The initiation of September sees an average high-temperature of a still moderately hot 75.6°F (24.2°C), showing minor variations from the previous month. Throughout the month of September, Potomac observes an average nighttime temperature of 57.6°F (14.2°C).Humidity
In September, the average relative humidity in Potomac is 77%.Rainfall
In September, in Potomac, Illinois, the rain falls for 12.1 days. Throughout September, 1.3" (33mm) of precipitation is accumulated. In Potomac, during the entire year, the rain falls for 146.3 days and collects up to 22.76" (578mm) of precipitation.Snowfall
In Potomac, Illinois, snow does not fall in May through October.Daylight
In Potomac, the average length of the day in September is 12h and 27min.On the first day of September in Potomac, sunrise is at 6:19 am and sunset at 7:22 pm. On the last day of the month, sunrise is at 6:47 am and sunset at 6:34 pm CDT.
Sunshine
In Potomac, the average sunshine in September is 8.7h.UV index
The average daily maximum UV index in September in Potomac, Illinois, is 5. A UV Index value of 3 to 5 symbolizes a moderate threat to health from unprotected exposure to Sun's UV rays for ordinary individuals.Note: A daily maximum UV index of 5 in September translates into the following instructions:
Act with care - The need to guard against sun damage is communicated. Protect yourself from the midday Sun's peak UV radiation by minimizing exposure. On sunny days, it's ideal to wear sunglasses that filter out UVA and UVB rays.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
Average temperature in September
Potomac, IL
- Average high temperature in September: 75.6°F
The warmest month (with the highest average high temperature) is July (81.1°F).
The month with the lowest average high temperature is January (31.5°F).
- Average low temperature in September: 57.6°F
The month with the highest average low temperature is July (64.4°F).
The coldest month (with the lowest average low temperature) is January (19.8°F).
Average pressure in September
Potomac, IL
- Average pressure in September: 30.03"Hg
The month with the highest atmospheric pressure is January (30.14"Hg).
The month with the lowest atmospheric pressure is June (29.93"Hg).
Average wind speed in September
Potomac, IL
- Average wind speed in September: 7.2mph
The windiest month (with the highest average wind speed) is January (10.5mph).
The calmest months (with the lowest average wind speed) are July and August (6.3mph).
Average humidity in September
Potomac, IL
- Average humidity in September: 77%
The month with the highest relative humidity is July (85%).
The month with the lowest relative humidity is October (72%).
Average rainfall in September
Potomac, IL
- Average rainfall in September: 1.3"
The wettest month (with the highest rainfall) is May (2.76").
The driest month (with the least rainfall) is February (1.18").
Average rainfall days in September
Potomac, IL
- Average rainfall days in September: 12.1 days
The month with the highest number of rainy days is July (17.7 days).
The month with the least rainy days is February (6.7 days).
Average snowfall in September
Potomac, IL
- Average snowfall in September: 0"
The month with the highest snowfall is February (2.32").
The months with the least snowfall are May, June, July, August, September and October (0").
Average snowfall days in September
Potomac, IL
- Average snowfall days in September: 0 days
The month with the highest number of snowfall days is January (9.8 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
Potomac, IL
- Average daylight in September: 12h and 24min
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: 8h and 42min
The month with the most sunshine is June (Average sunshine: 10h and 0min).
The month with the least sunshine is January (Average sunshine: 3h and 54min).
Average sunshine days in September
Potomac, IL
- Average sunshine days in September: 15.3 days
The month with the most sunshine days is November (18.7 days).
The month with the least sunshine days is July (9.5 days).
Average UV index in September
Potomac, 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 December (UV index 1).
Average cloud cover in September
Potomac, IL
- Average cloud cover in September: 33
The month with the most cloud cover is January (Cloud cover 59).
The months with the least cloud cover are June, August and September (Cloud cover 33).
Average visibility in September
Potomac, 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).
