September weather forecastLemont, IL
September
Weather in September
September, the first month of the autumn in Lemont, is still a warm month, with an average temperature fluctuating between 57.4°F (14.1°C) and 74.3°F (23.5°C).Temperature
As September commences, the average high-temperature subtly reduces, transitioning from 80.2°F (26.8°C) in August to a still moderately hot 74.3°F (23.5°C). During the nights in September, Lemont experiences a consistent average temperature of 57.4°F (14.1°C).Humidity
In September, the average relative humidity is 76%.Rainfall
In Lemont, in September, it is raining for 13.5 days, with typically 1.77" (45mm) of accumulated precipitation. In Lemont, during the entire year, the rain falls for 145.4 days and collects up to 22.83" (580mm) of precipitation.Snowfall
In Lemont, snow does not fall in June through September.Daylight
In Lemont, the average length of the day in September is 12h and 28min.On the first day of September in Lemont, sunrise is at 6:18 am and sunset at 7:24 pm. On the last day of the month, sunrise is at 6:48 am and sunset at 6:34 pm CDT.
Sunshine
In Lemont, the average sunshine in September is 8.7h.UV index
In Lemont, the average daily maximum UV index in September is 4. A UV Index value of 3 to 5 symbolizes a moderate health risk from unprotected exposure to Sun's UV rays for the ordinary person.Note: The UV index of 4 in September translates into these instructions:
Guard yourself - Avoiding sunburn is suggested. UV radiation from the Sun is most dangerous during midday; take precautions and seek shade. To mitigate harm from sun exposure, pick sunglasses offering UVA and UVB defense.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
Average temperature in September
Lemont, IL
- Average high temperature in September: 74.3°F
The warmest month (with the highest average high temperature) is July (81.9°F).
The month with the lowest average high temperature is January (28.8°F).
- Average low temperature in September: 57.4°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 (17.1°F).
Average pressure in September
Lemont, IL
- Average pressure in September: 30.03"Hg
The month with the highest atmospheric pressure is January (30.11"Hg).
The month with the lowest atmospheric pressure is June (29.92"Hg).
Average wind speed in September
Lemont, IL
- Average wind speed in September: 7mph
The windiest month (with the highest average wind speed) is January (9.7mph).
The calmest month (with the lowest average wind speed) is August (6mph).
Average humidity in September
Lemont, IL
- Average humidity in September: 76%
The months with the highest relative humidity are January and February (83%).
The month with the lowest relative humidity is October (73%).
Average rainfall in September
Lemont, IL
- Average rainfall in September: 1.77"
The wettest month (with the highest rainfall) is May (2.83").
The driest month (with the least rainfall) is December (1.06").
Average rainfall days in September
Lemont, IL
- Average rainfall days in September: 13.5 days
The month with the highest number of rainy days is July (18.1 days).
The month with the least rainy days is February (4.9 days).
Average snowfall in September
Lemont, IL
- Average snowfall in September: 0"
The month with the highest snowfall is January (3.11").
The months with the least snowfall are June, July, August and September (0").
Average snowfall days in September
Lemont, IL
- Average snowfall days in September: 0 days
The month with the highest number of snowfall days is January (12.1 days).
The months with the least snowfall days are June, July, August and September (0 days).
Average daylight in September /
Average sunshine in September
Lemont, IL
- Average daylight in September: 12h and 30min
The month with the longest days is June (Average daylight: 15h and 12min).
The month with the shortest days is December (Average daylight: 9h and 12min).
- Average sunshine in September: 8h and 42min
The months with the most sunshine are July and August (Average sunshine: 9h and 54min).
The month with the least sunshine is January (Average sunshine: 3h and 48min).
Average sunshine days in September
Lemont, IL
- Average sunshine days in September: 14.4 days
The month with the most sunshine days is November (18.4 days).
The month with the least sunshine days is July (9.3 days).
Average UV index in September
Lemont, IL
- Average UV index in September: 4
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
Lemont, IL
- Average cloud cover in September: 32
The month with the most cloud cover is January (Cloud cover 60).
The month with the least cloud cover is August (Cloud cover 31).
Average visibility in September
Lemont, IL
- Average visibility in September: 6mi
The months with the highest visibility are March, April, May, June, July, August, September, October, November and December (6mi).
The months with the lowest visibility are January and February (5mi).
