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 pleasant 72.9°F (22.7°C) from August's warm 78.4°F (25.8°C). Shannon's average low-temperature in September is measured at a cool 54.5°F (12.5°C).Humidity
The average relative humidity in September is 79%.Rainfall
In Shannon, Illinois, in September, it is raining for 10.7 days, with typically 1.5" (38mm) of accumulated precipitation. In Shannon, during the entire year, the rain falls for 130.8 days and collects up to 17.95" (456mm) of precipitation.Snowfall
In Shannon, snow does not fall in May through September.Daylight
The average length of the day in September is 12h and 28min.On the first day of September, sunrise is at 6:25 am and sunset at 7:32 pm. On the last day of the month, sunrise is at 6:55 am and sunset at 6:41 pm CDT.
Sunshine
In September, the average sunshine is 9h.UV index
The average daily maximum UV index in September is 4. A UV Index of 3 to 5 symbolizes a medium health hazard from exposure to the Sun's UV rays for the average person.Note: During September, 4 as the daily maximum UV index converts into the following advice:
Adopt protective measures - It is advised to guard against sun damage. Midday Sun has the strongest UV rays, making it crucial to limit exposure and find shade. Sun-related eye harm can be minimized with proper sunglasses offering UVA and UVB coverage.
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Data Sources | Weather Forecasting & Climate
Frequently asked questions
What are the temperatures in September?
What is the average humidity in September in Shannon?
How many days does it rain in September in Shannon?
When it does not snow?
Does it snow in September?
What is the average length of the day in September?
When is the sunrise / sunset in September?
How long on average sun shines in September?
What is the UV index reading in September in Shannon?
Average temperature in September
Shannon, IL
- Average high temperature in September: 72.9°F
The warmest month (with the highest average high temperature) is July (79.9°F).
The month with the lowest average high temperature is January (25.9°F).
- Average low temperature in September: 54.5°F
The month with the highest average low temperature is July (63.3°F).
The coldest month (with the lowest average low temperature) is January (13.5°F).
Average pressure in September
Shannon, 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 (29.91"Hg).
Average wind speed in September
Shannon, IL
- Average wind speed in September: 7.6mph
The windiest month (with the highest average wind speed) is April (10.4mph).
The calmest month (with the lowest average wind speed) is August (6.5mph).
Average humidity in September
Shannon, IL
- Average humidity in September: 79%
The month with the highest relative humidity is January (87%).
The month with the lowest relative humidity is October (75%).
Average rainfall in September
Shannon, IL
- Average rainfall in September: 1.5"
The wettest month (with the highest rainfall) is May (2.76").
The driest months (with the least rainfall) are January and February (0.71").
Average rainfall days in September
Shannon, IL
- Average rainfall days in September: 10.7 days
The month with the highest number of rainy days is May (17.9 days).
The month with the least rainy days is February (4.4 days).
Average snowfall in September
Shannon, IL
- Average snowfall in September: 0"
The month with the highest snowfall is January (2.64").
The months with the least snowfall are May, June, July, August and September (0").
Average snowfall days in September
Shannon, IL
- Average snowfall days in September: 0 days
The month with the highest number of snowfall days is January (11.2 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
Shannon, 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: 9h and 0min
The month with the most sunshine is July (Average sunshine: 9h and 48min).
The month with the least sunshine is January (Average sunshine: 3h and 42min).
Average sunshine days in September
Shannon, IL
- Average sunshine days in September: 17.8 days
The month with the most sunshine days is November (19.7 days).
The month with the least sunshine days is June (10 days).
Average UV index in September
Shannon, IL
- Average UV index in September: 4
The month with the highest UV index is July (UV index 6).
The months with the lowest UV index are January and December (UV index 1).
Average cloud cover in September
Shannon, 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 September (Cloud cover 32).
Average visibility in September
Shannon, IL
- Average visibility in September: 6mi
The months with the highest visibility are February, March, April, May, June, September, October, November and December (6mi).
The months with the lowest visibility are January, July and August (5mi).
Shannon, Illinois, USA
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