September weather forecastMonticello, IL
September
Weather in September
September, the first month of the autumn in Monticello, is still a warm month, with an average temperature varying between 76.6°F (24.8°C) and 58.3°F (14.6°C).Temperature
The shift into September finds Monticello, Illinois, at an average high-temperature of a still warm 76.6°F (24.8°C), closely comparable to August's conditions. Throughout September, Monticello witnesses a nighttime temperature average of 58.3°F (14.6°C).Humidity
In September, the average relative humidity is 76%.Rainfall
In Monticello, in September, it is raining for 10.2 days, with typically 0.98" (25mm) of accumulated precipitation. Throughout the year, there are 127.9 rainfall days, and 16.61" (422mm) of precipitation is accumulated.Snowfall
May through October are months without snowfall.Daylight
In September, the average length of the day is 12h and 26min.On the first day of the month, sunrise is at 6:22 am and sunset at 7:25 pm. On the last day of September, sunrise is at 6:50 am and sunset at 6:37 pm CDT.
Sunshine
In September, the average sunshine is 8.9h.UV index
In Monticello, the average daily maximum UV index in September is 5. A UV Index reading of 3 to 5 represents a moderate health risk from unsafe exposure to UV radiation for the ordinary person.Note: In September, the average maximum UV index of 5 translates into the following recommendations:
Take necessary precautions - Suggestions to elude sunburn are provided. The Sun's radiation is especially intense around midday; try to stay in shade during this period. Enhance your sun protection with tightly woven, yet airy clothing.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
Average temperature in September
Monticello, IL
- Average high temperature in September: 76.6°F
The warmest month (with the highest average high temperature) is July (81.9°F).
The month with the lowest average high temperature is January (32.4°F).
- Average low temperature in September: 58.3°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 (20.3°F).
Average pressure in September
Monticello, IL
- Average pressure in September: 30.03"Hg
The month with the highest atmospheric pressure is January (30.14"Hg).
The month with the lowest atmospheric pressure is June (29.92"Hg).
Average wind speed in September
Monticello, IL
- Average wind speed in September: 7.4mph
The windiest month (with the highest average wind speed) is January (10.9mph).
The calmest month (with the lowest average wind speed) is August (6.4mph).
Average humidity in September
Monticello, IL
- Average humidity in September: 76%
The month with the highest relative humidity is July (85%).
The month with the lowest relative humidity is October (70%).
Average rainfall in September
Monticello, IL
- Average rainfall in September: 0.98"
The wettest month (with the highest rainfall) is May (2.09").
The driest month (with the least rainfall) is December (0.91").
Average rainfall days in September
Monticello, IL
- Average rainfall days in September: 10.2 days
The month with the highest number of rainy days is May (16.3 days).
The month with the least rainy days is February (5.2 days).
Average snowfall in September
Monticello, IL
- Average snowfall in September: 0"
The month with the highest snowfall is January (2.05").
The months with the least snowfall are May, June, July, August, September and October (0").
Average snowfall days in September
Monticello, 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, September and October (0 days).
Average daylight in September /
Average sunshine in September
Monticello, IL
- Average daylight in September: 12h and 24min
The month with the longest days is June (Average daylight: 15h and 0min).
The month with the shortest days is December (Average daylight: 9h and 24min).
- Average sunshine in September: 8h and 54min
The month with the most sunshine is June (Average sunshine: 10h and 6min).
The month with the least sunshine is January (Average sunshine: 3h and 54min).
Average sunshine days in September
Monticello, IL
- Average sunshine days in September: 17.6 days
The month with the most sunshine days is November (19.6 days).
The month with the least sunshine days is May (12.3 days).
Average UV index in September
Monticello, 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
Monticello, IL
- Average cloud cover in September: 32
The month with the most cloud cover is January (Cloud cover 57).
The months with the least cloud cover are June, August and September (Cloud cover 32).
Average visibility in September
Monticello, IL
- Average visibility in September: 6mi
The months with the highest visibility are January, February, March, April, May, June, September, October, November and December (6mi).
The months with the lowest visibility are July and August (5mi).
