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
Dewey's weather, upon September's arrival, documents an average high-temperature of a still warm 75.9°F (24.4°C), nearly identical to the prior month. Dewey, during the nights of September, experiences an average temperature drop to a mild 57.6°F (14.2°C).Humidity
The average relative humidity in September is 77%.Rainfall
In Dewey, during September, the rain falls for 9.1 days and regularly aggregates up to 0.67" (17mm) of precipitation. In Dewey, during the entire year, the rain falls for 115.9 days and collects up to 10.87" (276mm) of precipitation.Snowfall
In Dewey, Illinois, snow does not fall in May through October.Daylight
The average length of the day in September is 12h and 27min.On the first day of September, sunrise is at 6:21 am and sunset at 7:24 pm. On the last day of the month, sunrise is at 6:49 am and sunset at 6:36 pm CDT.
Sunshine
In September, the average sunshine is 8.9h.UV index
The average daily maximum UV index in September is 5. A UV Index reading of 3 to 5 represents a moderate threat to health from exposure to the Sun's UV rays for the ordinary person.Note: In September, the maximum UV index of 5 transforms into these recommendations:
Guard yourself - An obligation to protect skin and eyes from harm exists. Midday Sun has the strongest UV rays, making it crucial to limit exposure and find shade. A hat with a broad brim is indispensable, filtering out up to half of UV rays.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
What are September temperatures?
What is the average humidity in September in Dewey?
How much does it rain in Dewey in September?
When it does not snow?
What is the average length of the day in September?
When is the sunrise / sunset in September?
How many hours of sunshine does Dewey have in September?
How high is the UV index in September?
Average temperature in September
Dewey, IL
- Average high temperature in September: 75.9°F
The warmest month (with the highest average high temperature) is July (81°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 (64.9°F).
The coldest month (with the lowest average low temperature) is January (19.8°F).
Average pressure in September
Dewey, 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 (29.92"Hg).
Average wind speed in September
Dewey, IL
- Average wind speed in September: 7.5mph
The windiest month (with the highest average wind speed) is January (10.9mph).
The calmest month (with the lowest average wind speed) is August (6.4mph).
Average humidity in September
Dewey, 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 (71%).
Average rainfall in September
Dewey, IL
- Average rainfall in September: 0.67"
The wettest month (with the highest rainfall) is May (1.46").
The driest month (with the least rainfall) is February (0.51").
Average rainfall days in September
Dewey, IL
- Average rainfall days in September: 9.1 days
The month with the highest number of rainy days is May (14.4 days).
The month with the least rainy days is January (4.5 days).
Average snowfall in September
Dewey, IL
- Average snowfall in September: 0"
The month with the highest snowfall is January (1.3").
The months with the least snowfall are May, June, July, August, September and October (0").
Average snowfall days in September
Dewey, IL
- Average snowfall days in September: 0 days
The month with the highest number of snowfall days is January (8.3 days).
The months with the least snowfall days are May, June, July, August, September and October (0 days).
Average daylight in September /
Average sunshine in September
Dewey, IL
- Average daylight in September: 12h and 2min
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 5min
The month with the most sunshine is June (Average sunshine: 10h and 6min).
The month with the least sunshine is January (Average sunshine: 4h and 0min).
Average sunshine days in September
Dewey, IL
- Average sunshine days in September: 17.5 days
The month with the most sunshine days is November (21.4 days).
The month with the least sunshine days is July (12.3 days).
Average UV index in September
Dewey, IL
- Average UV index in September: 5
The months with the highest UV index are June, July and August (UV index 6).
The months with the lowest UV index are January, February, November and December (UV index 2).
Average cloud cover in September
Dewey, IL
- Average cloud cover in September: 32
The month with the most cloud cover is January (Cloud cover 58).
The month with the least cloud cover is August (Cloud cover 31).
Average visibility in September
Dewey, 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).
Dewey, Illinois, USA
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