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
The transition into September subtly indicates a reduction in the average high-temperature, down to a still warm 74.3°F (23.5°C) from August's moderately hot 81.1°F (27.3°C). September in Darien witnesses an average low-temperature hovering around a moderate 57.9°F (14.4°C).Humidity
The average relative humidity in September is 75%.Rainfall
In Darien, during September, the rain falls for 11.5 days and regularly aggregates up to 1.18" (30mm) of precipitation. In Darien, during the entire year, the rain falls for 118.5 days and collects up to 13.74" (349mm) of precipitation.Snowfall
In Darien, snow does not fall in May through September.Daylight
In Darien, the average length of the day in September is 12h and 28min.On the first day of the month, sunrise is at 6:18 am and sunset at 7:24 pm. On the last day of September, sunrise is at 6:48 am and sunset at 6:34 pm CDT.
Sunshine
In September, the average sunshine is 8.7h.UV index
In September, the average daily maximum UV index is 4. A UV Index reading of 3 to 5 represents a medium vulnerability from unprotected exposure to Sun's UV rays for ordinary individuals.Note: The maximum UV index of 4 during September translates into these guidelines:
Take care. Persons with lighter skin might suffer burns in less than 30 minutes. Protect yourself from the midday Sun's peak UV radiation by minimizing exposure. 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
What is the average September temperature?
What is the average humidity in September?
How many days does it rain in September?
When it does not snow?
Does it snow in September?
How many hours of daylight does Darien have in September?
When are sunrise and sunset in September?
How long on average sun shines in September?
What is the UV index reading in September?
Average temperature in September
Darien, IL
- Average high temperature in September: 74.3°F
The warmest month (with the highest average high temperature) is July (82.4°F).
The month with the lowest average high temperature is January (28.8°F).
- Average low temperature in September: 57.9°F
The month with the highest average low temperature is July (66.4°F).
The coldest month (with the lowest average low temperature) is January (17.1°F).
Average pressure in September
Darien, 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
Darien, 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 (6.1mph).
Average humidity in September
Darien, IL
- Average humidity in September: 75%
The months with the highest relative humidity are January and February (82%).
The month with the lowest relative humidity is October (72%).
Average rainfall in September
Darien, IL
- Average rainfall in September: 1.18"
The wettest month (with the highest rainfall) is May (1.97").
The driest month (with the least rainfall) is December (0.63").
Average rainfall days in September
Darien, IL
- Average rainfall days in September: 11.5 days
The month with the highest number of rainy days is May (14.9 days).
The month with the least rainy days is February (4.2 days).
Average snowfall in September
Darien, IL
- Average snowfall in September: 0"
The month with the highest snowfall is February (2.28").
The months with the least snowfall are May, June, July, August and September (0").
Average snowfall days in September
Darien, IL
- Average snowfall days in September: 0 days
The month with the highest number of snowfall days is January (9.7 days).
The months with the least snowfall days are June, July, August and September (0 days).
Average daylight in September /
Average sunshine in September
Darien, IL
- Average daylight in September: 12h and 3min
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 4min
The month with the most sunshine is August (Average sunshine: 10h and 0min).
The month with the least sunshine is January (Average sunshine: 3h and 42min).
Average sunshine days in September
Darien, IL
- Average sunshine days in September: 16.1 days
The month with the most sunshine days is December (20.7 days).
The month with the least sunshine days is July (11.8 days).
Average UV index in September
Darien, 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 January (UV index 1).
Average cloud cover in September
Darien, IL
- Average cloud cover in September: 32
The month with the most cloud cover is January (Cloud cover 61).
The month with the least cloud cover is August (Cloud cover 31).
Average visibility in September
Darien, 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).
Darien, Illinois, USA
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