September weather forecastMattoon, IL
September
Weather in September
September, the first month of the autumn in Mattoon, is also a moderately hot month, with an average temperature fluctuating between 58.5°F (14.7°C) and 77.2°F (25.1°C).Temperature
September brings a marginal elevation to a still moderately hot 77.2°F (25.1°C) from August's 81.1°F (27.3°C) in Mattoon's average high-temperatures. In Mattoon, an average temperature of 58.5°F (14.7°C) is noted during September nights.Humidity
In September, the average relative humidity is 76%.Rainfall
In September, the rain falls for 12.1 days. Throughout September, 1.38" (35mm) of precipitation is accumulated. Throughout the year, in Mattoon, there are 148 rainfall days, and 25.63" (651mm) of precipitation is accumulated.Snowfall
In Mattoon, snow does not fall in May through September.Daylight
The average length of the day in September is 12h and 26min.On the first day of the month, sunrise is at 6:22 am and sunset at 7:23 pm. On the last day of September, sunrise is at 6:49 am and sunset at 6:37 pm CDT.
Sunshine
The average sunshine in September is 8.9h.UV index
In September, the average daily maximum UV index is 5. A UV Index value of 3 to 5 symbolizes a medium health hazard from unsafe exposure to UV radiation for ordinary individuals.Note: The maximum UV index of 5 during September translates into these guidelines:
Guard yourself - Avoiding sunburn is suggested. Direct exposure to the Sun's intense radiation around midday should be avoided for health reasons. In bright sunlight, prioritize sunglasses that grant protection from UVA and UVB radiation.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
Average temperature in September
Mattoon, IL
- Average high temperature in September: 77.2°F
The warmest month (with the highest average high temperature) is July (82°F).
The month with the lowest average high temperature is January (34°F).
- Average low temperature in September: 58.5°F
The month with the highest average low temperature is July (65.8°F).
The coldest month (with the lowest average low temperature) is January (21.9°F).
Average pressure in September
Mattoon, IL
- Average pressure in September: 30.03"Hg
The month with the highest atmospheric pressure is January (30.15"Hg).
The month with the lowest atmospheric pressure is June (29.93"Hg).
Average wind speed in September
Mattoon, IL
- Average wind speed in September: 7.1mph
The windiest month (with the highest average wind speed) is January (10.7mph).
The calmest month (with the lowest average wind speed) is July (6.2mph).
Average humidity in September
Mattoon, IL
- Average humidity in September: 76%
The month with the highest relative humidity is July (83%).
The month with the lowest relative humidity is October (70%).
Average rainfall in September
Mattoon, IL
- Average rainfall in September: 1.38"
The wettest month (with the highest rainfall) is April (3.31").
The driest month (with the least rainfall) is February (1.3").
Average rainfall days in September
Mattoon, IL
- Average rainfall days in September: 12.1 days
The month with the highest number of rainy days is May (16.8 days).
The month with the least rainy days is February (7.8 days).
Average snowfall in September
Mattoon, IL
- Average snowfall in September: 0"
The month with the highest snowfall is December (2.13").
The months with the least snowfall are May, June, July, August and September (0").
Average snowfall days in September
Mattoon, IL
- Average snowfall days in September: 0 days
The month with the highest number of snowfall days is January (8.1 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
Mattoon, 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 24min).
- Average sunshine in September: 8h and 54min
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 0min).
Average sunshine days in September
Mattoon, IL
- Average sunshine days in September: 15.7 days
The month with the most sunshine days is October (18.3 days).
The month with the least sunshine days is July (10.6 days).
Average UV index in September
Mattoon, IL
- Average UV index in September: 5
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
Mattoon, IL
- Average cloud cover in September: 32
The month with the most cloud cover is January (Cloud cover 56).
The month with the least cloud cover is June (Cloud cover 31).
Average visibility in September
Mattoon, 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).
