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
As Riverdale enters September, the average high-temperature subtly lowers from the 79.3°F (26.3°C) of August to a still warm 73.8°F (23.2°C). In the month of September, the temperature generally rests at an average low of 59.2°F (15.1°C).Humidity
The average relative humidity in September is 75%.Rainfall
In Riverdale, in September, during 9.8 rainfall days, 0.91" (23mm) of precipitation is typically accumulated. In Riverdale, during the entire year, the rain falls for 110.3 days and collects up to 10.31" (262mm) of precipitation.Snowfall
In Riverdale, Illinois, snow does not fall in May through September.Daylight
In September, the average length of the day in Riverdale, Illinois, is 12h and 28min.On the first day of the month, sunrise is at 6:17 am and sunset at 7:23 pm. On the last day of September, in Riverdale, Illinois, sunrise is at 6:47 am and sunset at 6:33 pm CDT.
Sunshine
The average sunshine in September in Riverdale is 8.9h.UV index
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 average individuals.Note: In September, the maximum UV index of 4 suggests this advice:
Make use of precautions - Shielding skin and eyes from injury is a requirement. Being exposed to the midday Sun can have harmful effects due to strong UV radiation; always take precautions. A wide-brimmed hat provides unparalleled sun protection for sensitive areas like the eyes, ears, and neck.
Frequently asked questions
What is the average September temperature in Riverdale?
What is the average humidity in September in Riverdale?
How much does it rain in Riverdale in September?
When it does not snow in Riverdale?
Does it snow in Riverdale in September?
How many hours of daylight does Riverdale have in September?
What time are sunrise and sunset in September in Riverdale?
How long on average sun shines in September in Riverdale?
What is the UV index intensity in September in Riverdale?
Average temperature in September
Riverdale, IL
- Average high temperature in September: 73.8°F
The warmest month (with the highest average high temperature) is July (80.1°F).
The month with the lowest average high temperature is January (29.8°F).
- Average low temperature in September: 59.2°F
The month with the highest average low temperature is July (66.9°F).
The coldest month (with the lowest average low temperature) is January (19.6°F).
Average pressure in September
Riverdale, IL
- Average pressure in September: 30.03"Hg
The month with the highest atmospheric pressure is January (30.11"Hg).
The month with the lowest atmospheric pressure is June (29.92"Hg).
Average wind speed in September
Riverdale, IL
- Average wind speed in September: 8mph
The windiest month (with the highest average wind speed) is January (11mph).
The calmest months (with the lowest average wind speed) are July and August (6.8mph).
Average humidity in September
Riverdale, IL
- Average humidity in September: 75%
The months with the highest relative humidity are January and February (82%).
The month with the lowest relative humidity is October (72%).
Average rainfall in September
Riverdale, IL
- Average rainfall in September: 0.91"
The wettest months (with the highest rainfall) are May and June (1.38").
The driest months (with the least rainfall) are February and December (0.47").
Average rainfall days in September
Riverdale, IL
- Average rainfall days in September: 9.8 days
The month with the highest number of rainy days is July (14 days).
The month with the least rainy days is February (4.1 days).
Average snowfall in September
Riverdale, IL
- Average snowfall in September: 0"
The month with the highest snowfall is January (1.1").
The months with the least snowfall are May, June, July, August and September (0").
Average snowfall days in September
Riverdale, IL
- Average snowfall days in September: 0 days
The month with the highest number of snowfall days is January (9.3 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
Riverdale, IL
- Average daylight in September: 12h and 3min
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: 8h and 5min
The month with the most sunshine is August (Average sunshine: 10h and 24min).
The month with the least sunshine is January (Average sunshine: 3h and 36min).
Average sunshine days in September
Riverdale, IL
- Average sunshine days in September: 16.9 days
The month with the most sunshine days is December (19.8 days).
The month with the least sunshine days is June (13.1 days).
Average UV index in September
Riverdale, IL
- Average UV index in September: 4
The months with the highest UV index are June, July and August (UV index 6).
The month with the lowest UV index is December (UV index 1).
Average cloud cover in September
Riverdale, IL
- Average cloud cover in September: 31
The month with the most cloud cover is January (Cloud cover 62).
The month with the least cloud cover is August (Cloud cover 28).
Average visibility in September
Riverdale, 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).
Riverdale, Illinois, USA
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