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
September marks a gentle change in average high-temperature, declining from August's 80.2°F (26.8°C) to a still moderately hot 74.3°F (23.5°C). September sees the temperature falling to a mean low of 57.4°F (14.1°C).Humidity
The average relative humidity in September in Romeoville is 76%.Rainfall
In Romeoville, in September, during 13.5 rainfall days, 1.77" (45mm) of precipitation is typically accumulated. Throughout the year, there are 145.4 rainfall days, and 22.83" (580mm) of precipitation is accumulated.Snowfall
In Romeoville, snow does not fall in June through September.Daylight
In Romeoville, the average length of the day in September is 12h and 28min.On the first day of September in Romeoville, sunrise is at 6:19 am and sunset at 7:25 pm. On the last day of the month, sunrise is at 6:48 am and sunset at 6:35 pm CDT.
Sunshine
In September, the average sunshine is 8.7h.UV index
In September, the average daily maximum UV index in Romeoville, Illinois, is 4. A UV Index of 3 to 5 symbolizes a medium health hazard from unsafe exposure to UV radiation for the ordinary person.Note: In September, the average maximum UV index of 4 translates into the following recommendations:
Act with care - The need to guard against sun damage is communicated. Exposing oneself to the midday Sun can be harmful due to the strong UV radiation; limit your time outside. Stay sun-safe with clothing that is both closely woven and worn loosely.
Frequently asked questions
What is the usual temperature for Romeoville in September?
What is the average humidity in September in Romeoville?
How much does it rain in Romeoville in September?
When it does not snow in Romeoville?
Does it snow in Romeoville in September?
What is the average length of the day in September in Romeoville?
What time are sunrise and sunset in September in Romeoville?
How long on average sun shines in September in Romeoville?
How high is the UV index in September in Romeoville?
Average temperature in September
Romeoville, 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
Romeoville, 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
Romeoville, 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
Romeoville, 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
Romeoville, 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
Romeoville, 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
Romeoville, 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
Romeoville, 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
Romeoville, IL
- Average daylight in September: 12h and 3min
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 4min
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
Romeoville, 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
Romeoville, 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
Romeoville, 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
Romeoville, 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).
Romeoville, Illinois, USA
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