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 shift from August to September coincides with a small decrease in the average high-temperature, down to a warm 80.2°F (26.8°C) from a tropical 86.5°F (30.3°C). During the September nights, an average temperature of 59.9°F (15.5°C) is observed.Humidity
In September, the average relative humidity is 74%.Rainfall
February and September are months with the least rain when the rain falls for 11.8 days and typically aggregates up to 1.81" (46mm) of rain.Snowfall
In Prairie du Rocher, snow does not fall in April through October.Daylight
In September, the average length of the day is 12h and 25min.On the first day of September, sunrise is at 6:30 am and sunset at 7:29 pm. On the last day of the month, sunrise is at 6:55 am and sunset at 6:44 pm CDT.
Sunshine
In September, the average sunshine is 9.2h.UV index
The average daily maximum UV index in September is 5. A UV Index value of 3 to 5 symbolizes a moderate threat to health from unprotected exposure to Sun's UV rays for the ordinary person.Note: A maximum daily UV index of 5 during September morphs into the following directions:
Make use of precautions - Shielding skin and eyes from injury is a requirement. The intensity of the Sun's UV radiation during midday suggests reducing time spent outdoors. Equip yourself with UVA and UVB-filtering sunglasses on clear, sunny days.
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?
What is the driest month?
How much does it rain in September?
When it does not snow?
How many hours of daylight does Prairie du Rocher have in September?
When is the sunrise / sunset in September?
How many hours of sunshine does Prairie du Rocher have in September?
How high is the UV index in September?
Average temperature in September
Prairie du Rocher, IL
- Average high temperature in September: 80.2°F
The warmest month (with the highest average high temperature) is July (87.6°F).
The month with the lowest average high temperature is January (39.6°F).
- Average low temperature in September: 59.9°F
The month with the highest average low temperature is July (68.4°F).
The coldest month (with the lowest average low temperature) is January (25.9°F).
Average pressure in September
Prairie du Rocher, IL
- Average pressure in September: 30.02"Hg
The month with the highest atmospheric pressure is January (30.16"Hg).
The month with the lowest atmospheric pressure is June (29.93"Hg).
Average wind speed in September
Prairie du Rocher, IL
- Average wind speed in September: 5.9mph
The windiest month (with the highest average wind speed) is January (9.4mph).
The calmest months (with the lowest average wind speed) are July and August (5.5mph).
Average humidity in September
Prairie du Rocher, IL
- Average humidity in September: 74%
The month with the highest relative humidity is May (79%).
The month with the lowest relative humidity is October (71%).
Average rainfall in September
Prairie du Rocher, IL
- Average rainfall in September: 1.81"
The wettest month (with the highest rainfall) is May (3.86").
The driest months (with the least rainfall) are February and September (1.81").
Average rainfall days in September
Prairie du Rocher, IL
- Average rainfall days in September: 11.8 days
The month with the highest number of rainy days is July (16.3 days).
The month with the least rainy days is January (7.3 days).
Average snowfall in September
Prairie du Rocher, IL
- Average snowfall in September: 0"
The months with the highest snowfall are January and February (2.36").
The months with the least snowfall are April, May, June, July, August, September and October (0").
Average snowfall days in September
Prairie du Rocher, IL
- Average snowfall days in September: 0 days
The month with the highest number of snowfall days is January (5.7 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
Prairie du Rocher, IL
- Average daylight in September: 12h and 2min
The month with the longest days is June (Average daylight: 14h and 48min).
The month with the shortest days is December (Average daylight: 9h and 36min).
- Average sunshine in September: 9h and 1min
The months with the most sunshine are June and July (Average sunshine: 10h and 24min).
The month with the least sunshine is January (Average sunshine: 4h and 36min).
Average sunshine days in September
Prairie du Rocher, IL
- Average sunshine days in September: 16.6 days
The month with the most sunshine days is December (19.7 days).
The month with the least sunshine days is July (12.3 days).
Average UV index in September
Prairie du Rocher, IL
- Average UV index in September: 5
The months with the highest UV index are May, June, July and August (UV index 6).
The months with the lowest UV index are January, February and December (UV index 2).
Average cloud cover in September
Prairie du Rocher, IL
- Average cloud cover in September: 30
The months with the most cloud cover are January and February (Cloud cover 49).
The months with the least cloud cover are June and August (Cloud cover 28).
Average visibility in September
Prairie du Rocher, 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).
Prairie du Rocher, Illinois, USA
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