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
The shift from August to September includes a minor decrease in the average high-temperature, lightly dropping from 84.4°F (29.1°C) to a still warm 76.1°F (24.5°C). In Mount Vernon, the average low-temperature during the month of September is a cool 55°F (12.8°C).Humidity
September and October, with an average relative humidity of 63%, are the least humid months.Rainfall
In Mount Vernon, during September, the rain falls for 9.2 days and regularly aggregates up to 1.18" (30mm) of precipitation. Throughout the year, in Mount Vernon, there are 93.2 rainfall days, and 11.3" (287mm) of precipitation is accumulated.Snowfall
In Mount Vernon, snow does not fall in May through September.Daylight
In Mount Vernon, the average length of the day in September is 12h and 29min.On the first day of September in Mount Vernon, sunrise is at 6:57 am and sunset at 8:08 pm. On the last day of the month, sunrise is at 7:30 am and sunset at 7:15 pm CDT.
Sunshine
The average sunshine in September is 8.9h.UV index
The average daily maximum UV index in September is 5. A UV Index of 3 to 5 symbolizes a moderate threat to health from exposure to the Sun's UV rays for the average person.Note: A maximum high UV index of 5 in September translates into the following recommendations:
Be cautious. Those with fair skin can be subjected to burns in fewer than 30 minutes. Midday Sun has the strongest UV rays, making it crucial to limit exposure and find shade. Opt for tightly woven and loose clothing to enhance protection from the Sun.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
What is the usual temperature for Mount Vernon in September?
What is the least humid month?
What is the average humidity in September in Mount Vernon?
How many days does it rain in September?
When it does not snow?
Does it snow in September?
How many hours of daylight does Mount Vernon have in September?
When is the sunrise / sunset in September?
How long on average sun shines in September?
What is the UV index intensity in September in Mount Vernon?
Average temperature in September
Mount Vernon, SD
- Average high temperature in September: 76.1°F
The warmest month (with the highest average high temperature) is July (85.6°F).
The month with the lowest average high temperature is January (24.4°F).
- Average low temperature in September: 55°F
The month with the highest average low temperature is July (64.6°F).
The coldest month (with the lowest average low temperature) is January (10.2°F).
Average pressure in September
Mount Vernon, SD
- Average pressure in September: 29.96"Hg
The months with the highest atmospheric pressure are January and February (30.16"Hg).
The month with the lowest atmospheric pressure is June (29.85"Hg).
Average wind speed in September
Mount Vernon, SD
- Average wind speed in September: 9.7mph
The windiest month (with the highest average wind speed) is April (11.2mph).
The calmest month (with the lowest average wind speed) is July (8.6mph).
Average humidity in September
Mount Vernon, SD
- Average humidity in September: 63%
The month with the highest relative humidity is January (87%).
The months with the lowest relative humidity are September and October (63%).
Average rainfall in September
Mount Vernon, SD
- Average rainfall in September: 1.18"
The wettest month (with the highest rainfall) is May (1.65").
The driest months (with the least rainfall) are February and November (0.28").
Average rainfall days in September
Mount Vernon, SD
- Average rainfall days in September: 9.2 days
The month with the highest number of rainy days is June (13.6 days).
The month with the least rainy days is February (1.9 days).
Average snowfall in September
Mount Vernon, SD
- Average snowfall in September: 0"
The month with the highest snowfall is February (1.42").
The months with the least snowfall are May, June, July, August and September (0").
Average snowfall days in September
Mount Vernon, SD
- Average snowfall days in September: 0 days
The month with the highest number of snowfall days is January (8.7 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, SD
- Average daylight in September: 12h and 3min
The month with the longest days is June (Average daylight: 15h and 24min).
The month with the shortest days is December (Average daylight: 9h and 0min).
- Average sunshine in September: 8h and 5min
The month with the most sunshine is July (Average sunshine: 11h and 6min).
The month with the least sunshine is January (Average sunshine: 4h and 24min).
Average sunshine days in September
Mount Vernon, SD
- Average sunshine days in September: 18.3 days
The month with the most sunshine days is November (23.4 days).
The month with the least sunshine days is June (12.8 days).
Average UV index in September
Mount Vernon, SD
- 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 January (UV index 1).
Average cloud cover in September
Mount Vernon, SD
- Average cloud cover in September: 26
The month with the most cloud cover is January (Cloud cover 52).
The month with the least cloud cover is July (Cloud cover 22).
Average visibility in September
Mount Vernon, SD
- 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).
Mount Vernon, South Dakota, USA
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