September weather forecastRock Island, IL
September
Weather in September
September, the first month of the autumn in Rock Island, is still a warm month, with temperature in the range of an average high of 75.4°F (24.1°C) and an average low of 56.3°F (13.5°C).Temperature
The transition to September results in a modest reduction in average high-temperature, moving from 80.8°F (27.1°C) in August to a still moderately hot 75.4°F (24.1°C). Throughout September, Rock Island registers a consistent average low-temperature of 56.3°F (13.5°C).Humidity
The average relative humidity in September is 76%.Rainfall
In September, the rain falls for 11.5 days. Throughout September, 2.05" (52mm) of precipitation is accumulated. In Rock Island, during the entire year, the rain falls for 138.1 days and collects up to 27.32" (694mm) of precipitation.Snowfall
In Rock Island, 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 the month, sunrise is at 6:29 am and sunset at 7:34 pm. On the last day of September, sunrise is at 6:58 am and sunset at 6:45 pm CDT.
Sunshine
In Rock Island, the average sunshine in September is 9.2h.UV index
In Rock Island, the average daily maximum UV index in September is 4. A UV Index value of 3 to 5 symbolizes a moderate threat to health from exposure to the Sun's UV radiation for the average person.Note: A maximum high UV index of 4 in September translates into the following recommendations:
Take measures. Individuals with light skin might experience burns in under 30 minutes. The solar radiation is most powerful near the mid-day, so the exposure to the direct Sun should be reduced accordingly. On days when the sun blazes, arm yourself with sunglasses that block UVA and UVB radiation.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
Average temperature in September
Rock Island, 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°F).
- Average low temperature in September: 56.3°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 (15.6°F).
Average pressure in September
Rock Island, 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 (29.9"Hg).
Average wind speed in September
Rock Island, 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
Rock Island, 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
Rock Island, IL
- Average rainfall in September: 2.05"
The wettest month (with the highest rainfall) is May (4.49").
The driest month (with the least rainfall) is February (1.1").
Average rainfall days in September
Rock Island, IL
- Average rainfall days in September: 11.5 days
The month with the highest number of rainy days is May (17.5 days).
The month with the least rainy days is January (4.3 days).
Average snowfall in September
Rock Island, IL
- Average snowfall in September: 0"
The month with the highest snowfall is January (3.98").
The months with the least snowfall are May, June, July, August and September (0").
Average snowfall days in September
Rock Island, IL
- Average snowfall days in September: 0 days
The month with the highest number of snowfall days is January (10.9 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
Rock Island, 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 12min
The month with the most sunshine is July (Average sunshine: 10h and 12min).
The month with the least sunshine is January (Average sunshine: 3h and 54min).
Average sunshine days in September
Rock Island, IL
- Average sunshine days in September: 17.4 days
The month with the most sunshine days is November (18.5 days).
The month with the least sunshine days is May (11.4 days).
Average UV index in September
Rock Island, IL
- Average UV index in September: 4
The months with the highest UV index are July and August (UV index 6).
The month with the lowest UV index is January (UV index 1).
Average cloud cover in September
Rock Island, 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
Rock Island, 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).
