September weather forecastMount Vernon, IA
September
Weather in September
September, the first month of the autumn in Mount Vernon, is also a moderately hot month, with an average temperature ranging between max 74.1°F (23.4°C) and min 54.9°F (12.7°C).Temperature
Stepping into September, Mount Vernon records an average high-temperature of a still warm 74.1°F (23.4°C), almost consistent with August. In September, the temperature drops to an average of 54.9°F (12.7°C) at night.Humidity
In Mount Vernon, the average relative humidity in September is 78%.Rainfall
In Mount Vernon, during September, the rain falls for 12 days and regularly aggregates up to 2.72" (69mm) of precipitation. Throughout the year, there are 147.9 rainfall days, and 31.57" (802mm) of precipitation is accumulated.Snowfall
May through September are months without snowfall.Daylight
In Mount Vernon, the average length of the day in September is 12h and 28min.On the first day of September, sunrise is at 6:32 am and sunset at 7:38 pm. On the last day of the month, sunrise is at 7:02 am and sunset at 6:48 pm CDT.
Sunshine
The average sunshine in September is 9.2h.UV index
The average daily maximum UV index in September is 4. A UV Index value of 3 to 5 symbolizes a medium health hazard from exposure to the Sun's UV rays for ordinary individuals.Note: A maximum high daily UV index of 4 during September translates into the following directions:
Guard yourself - Precautionary measures against sun damage are advocated. The Sun is most powerful around mid-day, so it's a good practice to reduce direct exposure. Employ a hat with a wide brim for robust protection, cutting UV exposure by half.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
Average temperature in September
Mount Vernon, IA
- Average high temperature in September: 74.1°F
The warmest month (with the highest average high temperature) is July (80.2°F).
The month with the lowest average high temperature is January (26.2°F).
- Average low temperature in September: 54.9°F
The month with the highest average low temperature is July (64.4°F).
The coldest month (with the lowest average low temperature) is January (14.2°F).
Average pressure in September
Mount Vernon, IA
- Average pressure in September: 30.02"Hg
The month with the highest atmospheric pressure is January (30.14"Hg).
The month with the lowest atmospheric pressure is June (29.9"Hg).
Average wind speed in September
Mount Vernon, IA
- Average wind speed in September: 8mph
The windiest month (with the highest average wind speed) is April (10.8mph).
The calmest months (with the lowest average wind speed) are July and August (7mph).
Average humidity in September
Mount Vernon, IA
- Average humidity in September: 78%
The month with the highest relative humidity is January (85%).
The month with the lowest relative humidity is October (73%).
Average rainfall in September
Mount Vernon, IA
- Average rainfall in September: 2.72"
The wettest month (with the highest rainfall) is May (5").
The driest month (with the least rainfall) is January (1.34").
Average rainfall days in September
Mount Vernon, IA
- Average rainfall days in September: 12 days
The month with the highest number of rainy days is May (19 days).
The months with the least rainy days are January and February (5.2 days).
Average snowfall in September
Mount Vernon, IA
- Average snowfall in September: 0"
The month with the highest snowfall is January (5.79").
The months with the least snowfall are May, June, July, August and September (0").
Average snowfall days in September
Mount Vernon, IA
- Average snowfall days in September: 0 days
The month with the highest number of snowfall days is January (12.7 days).
The months with the least snowfall days are June, July, August and September (0 days).
Average daylight in September /
Average sunshine in September
Mount Vernon, IA
- Average daylight in September: 12h and 30min
The month with the longest days is June (Average daylight: 15h and 12min).
The month with the shortest days is December (Average daylight: 9h and 12min).
- Average sunshine in September: 9h and 12min
The months with the most sunshine are July and August (Average sunshine: 9h and 48min).
The month with the least sunshine is January (Average sunshine: 4h and 0min).
Average sunshine days in September
Mount Vernon, IA
- Average sunshine days in September: 15.9 days
The month with the most sunshine days is November (17 days).
The month with the least sunshine days is June (8.1 days).
Average UV index in September
Mount Vernon, IA
- Average UV index in September: 4
The month with the highest UV index is July (UV index 6).
The month with the lowest UV index is December (UV index 1).
Average cloud cover in September
Mount Vernon, IA
- Average cloud cover in September: 31
The month with the most cloud cover is January (Cloud cover 58).
The months with the least cloud cover are August and September (Cloud cover 31).
Average visibility in September
Mount Vernon, IA
- Average visibility in September: 6mi
The months with the highest visibility are January, February, March, April, May, June, August, September, October, November and December (6mi).
The month with the lowest visibility is July (5mi).
