September weather forecastJefferson, SD
September
Weather in September
The first month of the autumn, September, is still a warm month in Jefferson, South Dakota, with an average temperature fluctuating between 76.1°F (24.5°C) and 55°F (12.8°C).Temperature
Jefferson's transition into September involves a gentle shift in temperature, receding from 82°F (27.8°C) in August to a still moderately hot 76.1°F (24.5°C). Throughout September, Jefferson witnesses a nighttime temperature average of 55°F (12.8°C).Humidity
In September, the average relative humidity in Jefferson is 70%.Rainfall
In Jefferson, in September, it is raining for 11.8 days, with typically 1.93" (49mm) of accumulated precipitation. Throughout the year, there are 122 rainfall days, and 21.61" (549mm) of precipitation is accumulated.Snowfall
June through September are months without snowfall.Daylight
In Jefferson, the average length of the day in September is 12h and 28min.On the first day of the month, sunrise is at 6:52 am and sunset at 7:59 pm. On the last day of September, sunrise is at 7:23 am and sunset at 7:08 pm CDT.
Sunshine
In September, the average sunshine is 8.8h.UV index
In Jefferson, the average daily maximum UV index in September is 5. A UV Index of 3 to 5 symbolizes a medium health hazard from exposure to the Sun's UV radiation for average individuals.Note: The maximum UV index of 5 during September leads to these instructions:
Ensure safety - Sun damage prevention is strongly urged. It's recommended to limit sun exposure when its radiation is at its peak during midday. Equip yourself with UVA and UVB-filtering sunglasses on clear, sunny days.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
Average temperature in September
Jefferson, SD
- Average high temperature in September: 76.1°F
The warmest month (with the highest average high temperature) is July (84°F).
The month with the lowest average high temperature is January (27°F).
- Average low temperature in September: 55°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 (13.1°F).
Average pressure in September
Jefferson, SD
- Average pressure in September: 29.98"Hg
The month with the highest atmospheric pressure is January (30.16"Hg).
The month with the lowest atmospheric pressure is June (29.86"Hg).
Average wind speed in September
Jefferson, SD
- Average wind speed in September: 9mph
The windiest month (with the highest average wind speed) is April (11.1mph).
The calmest month (with the lowest average wind speed) is July (7.6mph).
Average humidity in September
Jefferson, SD
- Average humidity in September: 70%
The month with the highest relative humidity is January (84%).
The month with the lowest relative humidity is October (65%).
Average rainfall in September
Jefferson, SD
- Average rainfall in September: 1.93"
The wettest months (with the highest rainfall) are May and June (3.03").
The driest month (with the least rainfall) is February (0.67").
Average rainfall days in September
Jefferson, SD
- Average rainfall days in September: 11.8 days
The month with the highest number of rainy days is June (17.8 days).
The month with the least rainy days is February (3.3 days).
Average snowfall in September
Jefferson, SD
- Average snowfall in September: 0"
The month with the highest snowfall is January (2.95").
The months with the least snowfall are June, July, August and September (0").
Average snowfall days in September
Jefferson, SD
- Average snowfall days in September: 0 days
The month with the highest number of snowfall days is January (9.6 days).
The months with the least snowfall days are June, July, August and September (0 days).
Average daylight in September /
Average sunshine in September
Jefferson, SD
- Average daylight in September: 12h and 30min
The month with the longest days is June (Average daylight: 15h and 18min).
The month with the shortest days is December (Average daylight: 9h and 6min).
- Average sunshine in September: 8h and 48min
The month with the most sunshine is July (Average sunshine: 10h and 42min).
The month with the least sunshine is January (Average sunshine: 4h and 24min).
Average sunshine days in September
Jefferson, SD
- Average sunshine days in September: 16.4 days
The month with the most sunshine days is November (20.9 days).
The month with the least sunshine days is June (9.7 days).
Average UV index in September
Jefferson, SD
- Average UV index in September: 5
The months with the highest UV index are June and July (UV index 6).
The month with the lowest UV index is January (UV index 1).
Average cloud cover in September
Jefferson, SD
- Average cloud cover in September: 28
The month with the most cloud cover is January (Cloud cover 52).
The month with the least cloud cover is July (Cloud cover 26).
Average visibility in September
Jefferson, 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).
