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
September's onset brings a negligible change in high-temperatures, falling from a warm 83.1°F (28.4°C) in August to a still moderately hot 74.3°F (23.5°C). Chelsea records a mean low-temperature of 52.9°F (11.6°C) in September.Humidity
The months with the lowest humidity in Chelsea are August and September, with an average relative humidity of 60%.Rainfall
In Chelsea, during September, the rain falls for 8.9 days and regularly aggregates up to 1.26" (32mm) of precipitation. In Chelsea, South Dakota, during the entire year, the rain falls for 97.2 days and collects up to 18.35" (466mm) of precipitation.Snowfall
June through September are months without snowfall.Daylight
In Chelsea, South Dakota, the average length of the day in September is 12h and 31min.On the first day of the month, sunrise is at 6:57 am and sunset at 8:11 pm. On the last day of September, sunrise is at 7:32 am and sunset at 7:16 pm CDT.
Sunshine
The average sunshine in September is 8.7h.UV index
In September, the average daily maximum UV index in Chelsea is 4. A UV Index estimate of 3 to 5 represents a moderate threat to health from exposure to the Sun's UV radiation for the average person.Note: The UV index of 4 in September translates into these instructions:
Preventative actions are necessary - The mandate to avoid skin and eye damage is in place. Considering the harmful UV rays from the Sun during midday, it's essential to reduce exposure. A hat with a generous brim can prevent nearly 50% of UV rays from reaching your eyes.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
What is the temperature in September in Chelsea?
What are the least humid months in Chelsea?
What is the average humidity in September in Chelsea?
How much does it rain in Chelsea in September?
When it does not snow in Chelsea?
Does it snow in Chelsea in September?
What is the average length of the day in September in Chelsea?
When is the sunrise / sunset in September in Chelsea?
How long on average sun shines in September in Chelsea?
How high is the UV index in September in Chelsea?
Average temperature in September
Chelsea, SD
- Average high temperature in September: 74.3°F
The warmest month (with the highest average high temperature) is July (84.7°F).
The month with the lowest average high temperature is January (20.7°F).
- Average low temperature in September: 52.9°F
The month with the highest average low temperature is July (63.1°F).
The coldest month (with the lowest average low temperature) is January (6.3°F).
Average pressure in September
Chelsea, SD
- Average pressure in September: 29.96"Hg
The month with the highest atmospheric pressure is February (30.17"Hg).
The month with the lowest atmospheric pressure is June (29.85"Hg).
Average wind speed in September
Chelsea, SD
- Average wind speed in September: 9.6mph
The windiest month (with the highest average wind speed) is April (10.6mph).
The calmest month (with the lowest average wind speed) is August (8.3mph).
Average humidity in September
Chelsea, SD
- Average humidity in September: 60%
The month with the highest relative humidity is January (88%).
The months with the lowest relative humidity are August and September (60%).
Average rainfall in September
Chelsea, SD
- Average rainfall in September: 1.26"
The wettest month (with the highest rainfall) is June (3.46").
The driest month (with the least rainfall) is January (0.59").
Average rainfall days in September
Chelsea, SD
- Average rainfall days in September: 8.9 days
The month with the highest number of rainy days is June (15 days).
The month with the least rainy days is February (2 days).
Average snowfall in September
Chelsea, SD
- Average snowfall in September: 0"
The month with the highest snowfall is January (3.82").
The months with the least snowfall are June, July, August and September (0").
Average snowfall days in September
Chelsea, SD
- Average snowfall days in September: 0 days
The month with the highest number of snowfall days is January (13 days).
The months with the least snowfall days are June, July, August and September (0 days).
Average daylight in September /
Average sunshine in September
Chelsea, SD
- Average daylight in September: 12h and 3min
The month with the longest days is June (Average daylight: 15h and 36min).
The month with the shortest days is December (Average daylight: 8h and 48min).
- Average sunshine in September: 8h and 4min
The month with the most sunshine is July (Average sunshine: 11h and 6min).
The month with the least sunshine is January (Average sunshine: 3h and 54min).
Average sunshine days in September
Chelsea, SD
- Average sunshine days in September: 18.7 days
The month with the most sunshine days is November (20.9 days).
The month with the least sunshine days is June (12.7 days).
Average UV index in September
Chelsea, SD
- Average UV index in September: 4
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 and November (UV index 1).
Average cloud cover in September
Chelsea, SD
- Average cloud cover in September: 26
The month with the most cloud cover is January (Cloud cover 57).
The months with the least cloud cover are July and August (Cloud cover 23).
Average visibility in September
Chelsea, SD
- Average visibility in September: 6mi
The months with the highest visibility are February, March, April, May, June, July, August, September, October, November and December (6mi).
The month with the lowest visibility is January (5mi).
Chelsea, South Dakota, USA
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