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 implies a soft temperature shift, with average high-temperatures reducing from August's 82.8°F (28.2°C) to a still warm 73.9°F (23.3°C). In Rapid City, the September nights cool down to an average low of 54°F (12.2°C).Humidity
The months with the lowest humidity are August and September, with an average relative humidity of 50%.Rainfall
In Rapid City, in September, it is raining for 7.8 days, with typically 0.94" (24mm) of accumulated precipitation. Throughout the year, there are 118.8 rainfall days, and 15.39" (391mm) of precipitation is accumulated.Snowfall
January through May, September through December are months with snowfall in Rapid City. September is the first month it typically snows. Throughout September, in the average 0.1 snowfall days, it receives 0.12" (3mm) of snow. In Rapid City, during the entire year, snow falls for 50.4 days and aggregates up to 24.41" (620mm) of snow.Daylight
In September, the average length of the day is 12h and 29min.On the first day of September, sunrise is at 6:17 am and sunset at 7:28 pm. On the last day of the month, sunrise is at 6:50 am and sunset at 6:34 pm MDT.
Sunshine
In Rapid City, the average sunshine in September is 10.4h.UV index
In Rapid City, the average daily maximum UV index in September is 4. A UV Index of 3 to 5 symbolizes a medium vulnerability from unprotected exposure to Sun's UV rays for ordinary individuals.Note: In September, a regular UV index of 4 translates into these guidelines:
Heed the precautions - Suggestions to avoid sunburn are made. Avoiding the Sun during its peak radiation time around midday is a healthy practice. For excellent sun protection for the eyes, ears, face, and neck, consider a wide-brim hat. Mark this! Snow reflection can nearly double the UV radiation intensity from the Sun.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
What is the average September temperature?
What are the least humid months?
What is the average humidity in September?
How many days does it rain in September?
When does it start to snow?
What is the average length of the day in September in Rapid City?
When is the sunrise / sunset in September?
How long on average sun shines in September?
How high is the UV index in September?
Average temperature in September
Rapid City, SD
- Average high temperature in September: 73.9°F
The warmest month (with the highest average high temperature) is July (84.7°F).
The month with the lowest average high temperature is December (32.5°F).
- Average low temperature in September: 54°F
The month with the highest average low temperature is July (63.3°F).
The coldest month (with the lowest average low temperature) is February (17.8°F).
Average pressure in September
Rapid City, SD
- Average pressure in September: 29.93"Hg
The month with the highest atmospheric pressure is January (30.14"Hg).
The month with the lowest atmospheric pressure is June (29.84"Hg).
Average wind speed in September
Rapid City, SD
- Average wind speed in September: 9.1mph
The windiest month (with the highest average wind speed) is April (10.3mph).
The calmest month (with the lowest average wind speed) is August (8.2mph).
Average humidity in September
Rapid City, SD
- Average humidity in September: 50%
The month with the highest relative humidity is January (77%).
The months with the lowest relative humidity are August and September (50%).
Average rainfall in September
Rapid City, SD
- Average rainfall in September: 0.94"
The wettest month (with the highest rainfall) is May (2.28").
The driest month (with the least rainfall) is January (0.43").
Average rainfall days in September
Rapid City, SD
- Average rainfall days in September: 7.8 days
The month with the highest number of rainy days is May (17.1 days).
The month with the least rainy days is December (4.8 days).
Average snowfall in September
Rapid City, SD
- Average snowfall in September: 0.12"
The month with the highest snowfall is April (5.43").
The months with the least snowfall are June, July and August (0").
Average snowfall days in September
Rapid City, SD
- Average snowfall days in September: 0.1 days
The month with the highest number of snowfall days is February (10.5 days).
The months with the least snowfall days are June, July and August (0 days).
Average daylight in September /
Average sunshine in September
Rapid City, 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: 8h and 54min).
- Average sunshine in September: 10h and 2min
The month with the most sunshine is August (Average sunshine: 11h and 48min).
The month with the least sunshine is February (Average sunshine: 5h and 54min).
Average sunshine days in September
Rapid City, SD
- Average sunshine days in September: 19.9 days
The month with the most sunshine days is November (20.2 days).
The month with the least sunshine days is May (11 days).
Average UV index in September
Rapid City, SD
- Average UV index in September: 4
The months with the highest UV index are June and July (UV index 6).
The months with the lowest UV index are January, February, November and December (UV index 2).
Average cloud cover in September
Rapid City, SD
- Average cloud cover in September: 18
The months with the most cloud cover are February and April (Cloud cover 38).
The month with the least cloud cover is August (Cloud cover 16).
Average visibility in September
Rapid City, 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).
Rapid City, South Dakota, USA
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