September weather forecast
Box Elder, SD

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Weather in September

As September arrives, Box Elder starts to experience a significant reduction in temperature, affecting the sunny, summer spirit. The city enters the transitional phase towards autumn with shorter days and a remarkable drop in the highest temperatures, marking the end of hot summer days. The level of rainfall increases slightly to 0.94" (24mm), adding a cooling effect to the environment. Colors start to change, forming a spectacular mosaic of autumn shades that precede the colder months. By the end of September, Box Elder is adorned with the typical autumn aura, ready to embrace the swift transition into full-fledged fall.

Temperature

Box Elder's progression into September involves a gentle drop in the average high-temperature, from 82.8°F (28.2°C) in August to a still warm 73.9°F (23.3°C). Box Elder records an average low-temperature of 54°F (12.2°C) throughout the month of September.

Humidity

August and September, with an average relative humidity of 50%, are the least humid months.

Rainfall

In Box Elder, in September, it is raining for 7.8 days, with typically 0.94" (24mm) of accumulated precipitation. In Box Elder, during the entire year, the rain falls for 118.8 days and collects up to 15.39" (391mm) of precipitation.

Snowfall

January through May, September through December are months with snowfall. 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 Box Elder, during the entire year, snow falls for 50.4 days and aggregates up to 24.41" (620mm) of snow.

Daylight

The average length of the day in September is 12h and 29min.
On the first day of the month, sunrise is at 6:16 am and sunset at 7:27 pm. On the last day of September, in Box Elder, sunrise is at 6:49 am and sunset at 6:34 pm MDT.

Sunshine

In September, the average sunshine is 10.4h.

UV index

In Box Elder, the average daily maximum UV index in September is 4. A UV Index reading of 3 to 5 represents a moderate health risk from unprotected exposure to Sun's UV rays for the average person.
Note: In September, a regular UV index of 4 translates into these guidelines:
Proceed with care. Light skin individuals may be exposed to burns in fewer than 30 minutes. To protect against the Sun's most potent rays, avoid direct exposure around midday. Select sunglasses that boast both UVA and UVB protection to limit the adverse effects of the sun on the eyes. Remember to consider! The UV radiation from the Sun can be intensified nearly twice by the reflection of snow.
Updated: Aug 16, 2024
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate

Frequently asked questions

What are September temperatures?

The average high-temperature and low-temperature during September are 73.9°F (23.3°C) and 54°F (12.2°C) respectively. The average heat index (a.k.a. 'real feel', 'apparent temperature'), which combines air temperature and relative humidity, in August is appraised at 84.2°F (29°C).

What is the least humid month?

August and September, with an average relative humidity of 50%, are the least humid months.

What is the average humidity in September?

The average relative humidity in September is 50%.

How many days does it rain in September?

In Box Elder, in September, it is raining for 7.8 days, with typically 0.94" (24mm) of accumulated precipitation.

When does it start to snow?

September is the first month it typically snows. Throughout September, in the average 0.1 snowfall days, it receives 0.12" (3mm) of snow.

How many hours of daylight does Box Elder have in September?

In September, the average day length is 12h and 29min.

When is the sunrise / sunset in September in Box Elder?

On the first day of September, sunrise is at 6:16 am and sunset at 7:27 pm. On the last day of the month, sunrise is at 6:49 am and sunset at 6:34 pm MDT.

How many hours of sunshine does Box Elder have in September?

In Box Elder, the average sunshine duration in September is 10.4h.

What is the UV index intensity in September?

The average daily maximum UV index in September is 4. A UV Index estimate of 3 to 5 represents a medium hazard to health from exposure to the Sun's UV radiation.
Average humidity
Average rainfall days
Average snowfall
Average snowfall days
Average daylight
Average sunshine
Average sunshine days
Average UV index
Average cloud cover
Average visibility

Average temperature in September
Box Elder, SD

Average temperature in September - Box Elder, 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
Box Elder, SD

Average pressure in September - Box Elder, 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
Box Elder, SD

Average wind speed in September - Box Elder, 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
Box Elder, SD

Average humidity in September - Box Elder, 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
Box Elder, SD

Average rainfall in September - Box Elder, 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
Box Elder, SD

Average rainfall days in September - Box Elder, 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
Box Elder, SD

Average snowfall in September - Box Elder, 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
Box Elder, SD

Average snowfall days in September - Box Elder, 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
Box Elder, SD

Average daylight in September / Average sunshine in September - Box Elder, 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
Box Elder, SD

Average sunshine days in September - Box Elder, 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
Box Elder, SD

Average UV index in September - Box Elder, 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
Box Elder, SD

Average cloud cover in September - Box Elder, 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
Box Elder, SD

Average visibility in September - Box Elder, 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).

Box Elder, South Dakota, USA

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