September weather forecastVandalia, IL
September
Weather in September
The first month of the autumn, September, is still a warm month in Vandalia, Illinois, with an average temperature ranging between min 59.4°F (15.2°C) and max 77.9°F (25.5°C).Temperature
September's onset brings an average high-temperature of a still moderately hot 77.9°F (25.5°C), showing a minute difference from August's 82.6°F (28.1°C). The temperature lowers to an average of 59.4°F (15.2°C) during September nights.Humidity
In September, the average relative humidity is 75%.Rainfall
In Vandalia, during September, the rain falls for 13.3 days and regularly aggregates up to 2.17" (55mm) of precipitation. In Vandalia, during the entire year, the rain falls for 164.1 days and collects up to 36.73" (933mm) of precipitation.Snowfall
May through October are months without snowfall.Daylight
In Vandalia, the average length of the day in September is 12h and 26min.On the first day of the month, sunrise is at 6:25 am and sunset at 7:26 pm. On the last day of September, in Vandalia, sunrise is at 6:52 am and sunset at 6:40 pm CDT.
Sunshine
In September, the average sunshine is 9.1h.UV index
In September, the average daily maximum UV index is 5. A UV Index reading of 3 to 5 represents a medium vulnerability from exposure to the Sun's UV rays for the ordinary person.Note: The daily maximum UV index of 5 in September interprets into the following advice:
Take precautions. Light skin individuals may get burned in less than 30 minutes. The Sun is at its harshest during midday; protect yourself by staying in shaded areas and minimizing exposure. Experience reduced UV exposure by about half when donning a wide-brim hat.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
Average temperature in September
Vandalia, IL
- Average high temperature in September: 77.9°F
The warmest month (with the highest average high temperature) is July (84°F).
The month with the lowest average high temperature is January (36°F).
- Average low temperature in September: 59.4°F
The month with the highest average low temperature is July (67.3°F).
The coldest month (with the lowest average low temperature) is January (23.4°F).
Average pressure in September
Vandalia, IL
- Average pressure in September: 30.03"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
Vandalia, IL
- Average wind speed in September: 6.6mph
The windiest month (with the highest average wind speed) is January (10.3mph).
The calmest months (with the lowest average wind speed) are July and August (6mph).
Average humidity in September
Vandalia, IL
- Average humidity in September: 75%
The month with the highest relative humidity is July (81%).
The month with the lowest relative humidity is October (71%).
Average rainfall in September
Vandalia, IL
- Average rainfall in September: 2.17"
The wettest month (with the highest rainfall) is June (4.57").
The driest month (with the least rainfall) is February (2.01").
Average rainfall days in September
Vandalia, IL
- Average rainfall days in September: 13.3 days
The month with the highest number of rainy days is May (18.3 days).
The month with the least rainy days is January (9.2 days).
Average snowfall in September
Vandalia, IL
- Average snowfall in September: 0"
The month with the highest snowfall is December (2.4").
The months with the least snowfall are May, June, July, August, September and October (0").
Average snowfall days in September
Vandalia, IL
- Average snowfall days in September: 0 days
The month with the highest number of snowfall days is January (8.3 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
Vandalia, IL
- Average daylight in September: 12h and 24min
The month with the longest days is June (Average daylight: 14h and 54min).
The month with the shortest days is December (Average daylight: 9h and 30min).
- Average sunshine in September: 9h and 6min
The month with the most sunshine is June (Average sunshine: 10h and 18min).
The month with the least sunshine is January (Average sunshine: 4h and 18min).
Average sunshine days in September
Vandalia, IL
- Average sunshine days in September: 14.7 days
The month with the most sunshine days is October (17.2 days).
The month with the least sunshine days is July (8.6 days).
Average UV index in September
Vandalia, IL
- Average UV index in September: 5
The months with the highest UV index are June, July and August (UV index 6).
The months with the lowest UV index are January, February, November and December (UV index 2).
Average cloud cover in September
Vandalia, IL
- Average cloud cover in September: 30
The month with the most cloud cover is January (Cloud cover 53).
The months with the least cloud cover are June, July and September (Cloud cover 30).
Average visibility in September
Vandalia, 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).
