September weather forecastJoliet, IL
September
Weather in September
September is an epitome of a transitional month in Joliet, with summer slowly yielding to the upcoming fall. The temperature drops moderately from August’s 80.1°F (26.7°C) to a comfortable 74.7°F (23.7°C). As autumn nears, daylight hours decrease while mild winds begin to sway, signalling a change in season. Humidity lessens, and condensation levels dip facilitating strikingly clear visibility.Temperature
September brings a minor shift in the average high-temperature, adjusting from a moderately hot 80.1°F (26.7°C) in August to a still warm 74.7°F (23.7°C). During September, Joliet's temperature averages to a moderate 56.7°F (13.7°C) at night.Humidity
In September, the average relative humidity is 78%.Rainfall
In Joliet, in September, it is raining for 12.5 days, with typically 2.48" (63mm) of accumulated precipitation. Throughout the year, in Joliet, there are 153.6 rainfall days, and 32.72" (831mm) of precipitation is accumulated.Snowfall
In Joliet, snow does not fall in May through October.Daylight
In Joliet, the average length of the day in September is 12h and 28min.On the first day of September, sunrise is at 6:19 am and sunset at 7:24 pm. On the last day of the month, sunrise is at 6:48 am and sunset at 6:35 pm CDT.
Sunshine
In Joliet, the average sunshine in September is 8.5h.UV index
In September, the average daily maximum UV index is 4. A UV Index of 3 to 5 symbolizes a moderate health risk from unsafe exposure to UV radiation for average individuals.Note: The maximum daily UV index of 4 in September interprets into the following recommendations:
Take necessary precautions - Defending against sun damage is advocated. Around midday, solar radiation is most harmful; hence, exposure should be limited. Prioritize a wide-brim hat for comprehensive sun defense for your face, neck, eyes, and ears.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
Average temperature in September
Joliet, IL
- Average high temperature in September: 74.7°F
The warmest month (with the highest average high temperature) is July (81.3°F).
The month with the lowest average high temperature is January (29.3°F).
- Average low temperature in September: 56.7°F
The month with the highest average low temperature is July (64.8°F).
The coldest month (with the lowest average low temperature) is January (17.4°F).
Average pressure in September
Joliet, IL
- Average pressure in September: 30.03"Hg
The month with the highest atmospheric pressure is January (30.12"Hg).
The month with the lowest atmospheric pressure is June (29.92"Hg).
Average wind speed in September
Joliet, IL
- Average wind speed in September: 6.9mph
The windiest month (with the highest average wind speed) is April (9.7mph).
The calmest month (with the lowest average wind speed) is August (5.9mph).
Average humidity in September
Joliet, IL
- Average humidity in September: 78%
The month with the highest relative humidity is February (83%).
The month with the lowest relative humidity is October (73%).
Average rainfall in September
Joliet, IL
- Average rainfall in September: 2.48"
The wettest month (with the highest rainfall) is May (4.41").
The driest month (with the least rainfall) is February (1.61").
Average rainfall days in September
Joliet, IL
- Average rainfall days in September: 12.5 days
The month with the highest number of rainy days is July (17.9 days).
The month with the least rainy days is February (5.7 days).
Average snowfall in September
Joliet, IL
- Average snowfall in September: 0"
The month with the highest snowfall is January (4.33").
The months with the least snowfall are May, June, July, August, September and October (0").
Average snowfall days in September
Joliet, IL
- Average snowfall days in September: 0 days
The month with the highest number of snowfall days is January (11.9 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
Joliet, IL
- Average daylight in September: 12h and 30min
The month with the longest days is June (Average daylight: 15h and 6min).
The month with the shortest days is December (Average daylight: 9h and 12min).
- Average sunshine in September: 8h and 30min
The month with the most sunshine is August (Average sunshine: 9h and 42min).
The month with the least sunshine is January (Average sunshine: 3h and 42min).
Average sunshine days in September
Joliet, IL
- Average sunshine days in September: 15 days
The month with the most sunshine days is November (18.1 days).
The month with the least sunshine days is June (10.4 days).
Average UV index in September
Joliet, IL
- Average UV index in September: 4
The months with the highest UV index are June and July (UV index 6).
The months with the lowest UV index are January and December (UV index 1).
Average cloud cover in September
Joliet, IL
- Average cloud cover in September: 34
The month with the most cloud cover is January (Cloud cover 60).
The months with the least cloud cover are August and September (Cloud cover 34).
Average visibility in September
Joliet, IL
- Average visibility in September: 6mi
The months with the highest visibility are March, April, May, June, September, October, November and December (6mi).
The months with the lowest visibility are January, February, July and August (5mi).
