September weather forecastGreen Rock, IL
September
Weather in September
The first month of the autumn, September, is also a moderately hot month in Green Rock, Illinois, with an average temperature fluctuating between 75.4°F (24.1°C) and 56.3°F (13.5°C).Temperature
The onset of September notes an average high-temperature of a still warm 75.4°F (24.1°C), subtly shifted from August's 80.6°F (27°C). An average minimum temperature of 56.3°F (13.5°C) marks the month of September.Humidity
In September, the average relative humidity is 76%.Rainfall
In Green Rock, during September, the rain falls for 6.9 days and regularly aggregates up to 0.75" (19mm) of precipitation. In Green Rock, during the entire year, the rain falls for 99.4 days and collects up to 9.57" (243mm) of precipitation.Snowfall
Months with snowfall are January through April, September through December. September is the first month it typically snows. Throughout September, in the average 0.1 snowfall days, it receives 0.04" (1mm) of snow. In Green Rock, during the entire year, snow falls for 24.5 days and aggregates up to 4.09" (104mm) of snow.Daylight
The average length of the day in September is 12h and 28min.On the first day of the month, sunrise is at 6:28 am and sunset at 7:33 pm. On the last day of September, sunrise is at 6:57 am and sunset at 6:44 pm CDT.
Sunshine
In Green Rock, the average sunshine in September is 9.1h.UV index
In September, the average daily maximum UV index is 4. A UV Index reading of 3 to 5 represents a moderate threat to health from unsafe exposure to UV radiation for the average person.Note: The maximum UV index of 4 during September translates into these guidelines:
Make use of precautions - Suggestions to resist sunburn are communicated. The most potent solar radiation is around mid-day, so one should minimize exposure to direct sunlight during this period. Sunglasses providing both UVA and UVB protection are non-negotiable on sunlit days. Consider this! The reflection from snow can almost double the intensity of the Sun's UV radiation.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
Average temperature in September
Green Rock, IL
- Average high temperature in September: 75.4°F
The warmest month (with the highest average high temperature) is July (81.7°F).
The month with the lowest average high temperature is January (28.2°F).
- Average low temperature in September: 56.3°F
The month with the highest average low temperature is July (64.8°F).
The coldest month (with the lowest average low temperature) is January (15.4°F).
Average pressure in September
Green Rock, IL
- Average pressure in September: 30.02"Hg
The month with the highest atmospheric pressure is January (30.13"Hg).
The month with the lowest atmospheric pressure is June (29.91"Hg).
Average wind speed in September
Green Rock, IL
- Average wind speed in September: 7.8mph
The windiest month (with the highest average wind speed) is April (10.6mph).
The calmest month (with the lowest average wind speed) is August (6.7mph).
Average humidity in September
Green Rock, IL
- Average humidity in September: 76%
The months with the highest relative humidity are January and July (83%).
The month with the lowest relative humidity is October (71%).
Average rainfall in September
Green Rock, IL
- Average rainfall in September: 0.75"
The wettest month (with the highest rainfall) is May (1.61").
The driest month (with the least rainfall) is December (0.35").
Average rainfall days in September
Green Rock, IL
- Average rainfall days in September: 6.9 days
The month with the highest number of rainy days is May (13.4 days).
The month with the least rainy days is January (3.2 days).
Average snowfall in September
Green Rock, IL
- Average snowfall in September: 0.04"
The month with the highest snowfall is January (1.26").
The months with the least snowfall are May, June, July and August (0").
Average snowfall days in September
Green Rock, IL
- Average snowfall days in September: 0.1 days
The month with the highest number of snowfall days is January (7.2 days).
The months with the least snowfall days are May, June, July and August (0 days).
Average daylight in September /
Average sunshine in September
Green Rock, IL
- Average daylight in September: 12h and 30min
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: 9h and 6min
The month with the most sunshine is July (Average sunshine: 10h and 6min).
The month with the least sunshine is January (Average sunshine: 3h and 54min).
Average sunshine days in September
Green Rock, IL
- Average sunshine days in September: 20.9 days
The month with the most sunshine days is December (22.4 days).
The month with the least sunshine days is June (14.4 days).
Average UV index in September
Green Rock, IL
- Average UV index in September: 4
The month with the highest UV index is July (UV index 6).
The month with the lowest UV index is January (UV index 1).
Average cloud cover in September
Green Rock, IL
- Average cloud cover in September: 31
The month with the most cloud cover is January (Cloud cover 58).
The month with the least cloud cover is August (Cloud cover 30).
Average visibility in September
Green Rock, 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).
