September weather forecast
Denby, SD

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Weather in September

The first month of the autumn, September, is still a warm month in Denby, South Dakota, with an average temperature fluctuating between 77°F (25°C) and 55.9°F (13.3°C).

Temperature

The arrival of September suggests a slight decrease in the average high-temperature, moving from a moderately hot 85.6°F (29.8°C) in August to a still warm 77°F (25°C). Throughout the September nights, Denby encounters a low-temperature of 55.9°F (13.3°C).

Humidity

The average relative humidity in September is 49%.

Rainfall

In Denby, during September, the rain falls for 6.1 days and regularly aggregates up to 1.02" (26mm) of precipitation. Throughout the year, there are 86.7 rainfall days, and 13.66" (347mm) of precipitation is accumulated.

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 0.04" (1mm) of snow. Throughout the year, there are 47.4 snowfall days, and 22.72" (577mm) of snow is accumulated.

Daylight

In September, the average length of the day is 12h and 29min.
On the first day of the month, sunrise is at 6:14 am and sunset at 7:23 pm. On the last day of September, sunrise is at 6:46 am and sunset at 6:31 pm MDT.

Sunshine

The average sunshine in September is 10.2h.

UV index

In Denby, 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 ordinary person.
Note: The maximum UV index, 4 during September, leads to the following recommendations:
Make use of precautions - It is urged to ward off sun damage. Midday Sun has the strongest UV rays, making it crucial to limit exposure and find shade. Clothes that are both tight-knit and comfortably loose are prime choices for sun protection. Take warning! The intensity of the Sun's UV radiation can be nearly amplified twice due to snow reflection.
Updated: Jul 25, 2024
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate

Frequently asked questions

What is the average September temperature?

In September, in Denby, the average high-temperature is 77°F (25°C), and the average low-temperature is 55.9°F (13.3°C). In August, the average heat index (a.k.a. 'real feel', 'felt air temperature'), which combines relative humidity and air temperature, is computed to be 86°F (30°C).

What is the average humidity in September in Denby?

The average relative humidity in September is 49%.

How much does it rain in September?

In Denby, during September, the rain falls for 6.1 days and regularly aggregates up to 1.02" (26mm) of precipitation.

When does it start snowing?

September is the first month it typically snows. Throughout September, in the average 0.1 snowfall days, it receives 0.04" (1mm) of snow.

What is the average length of the day in September?

The average day length in September is 12h and 29min.

What time are sunrise and sunset in September?

On the first day of September, sunrise is at 6:14 am and sunset at 7:23 pm. On the last day of the month, sunrise is at 6:46 am and sunset at 6:31 pm MDT.

How long on average sun shines in September?

The average sunshine duration in September is 10.2h.

How high is the UV index in September?

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

Average temperature in September
Denby, SD

Average temperature in September - Denby, SD
  • Average high temperature in September: 77°F

The warmest month (with the highest average high temperature) is July (87.6°F).
The month with the lowest average high temperature is December (32.4°F).

  • Average low temperature in September: 55.9°F

The month with the highest average low temperature is July (65.5°F).
The coldest month (with the lowest average low temperature) is January (18.1°F).

Average pressure in September
Denby, SD

Average pressure in September - Denby, SD
  • Average pressure in September: 29.94"Hg

The month with the highest atmospheric pressure is January (30.13"Hg).
The month with the lowest atmospheric pressure is June (29.85"Hg).

Average wind speed in September
Denby, SD

Average wind speed in September - Denby, SD
  • Average wind speed in September: 11.2mph

The windiest month (with the highest average wind speed) is April (12.2mph).
The calmest month (with the lowest average wind speed) is August (10.2mph).

Average humidity in September
Denby, SD

Average humidity in September - Denby, SD
  • Average humidity in September: 49%

The month with the highest relative humidity is January (80%).
The month with the lowest relative humidity is August (48%).

Average rainfall in September
Denby, SD

Average rainfall in September - Denby, SD
  • Average rainfall in September: 1.02"

The wettest month (with the highest rainfall) is May (2.13").
The driest month (with the least rainfall) is January (0.55").

Average rainfall days in September
Denby, SD

Average rainfall days in September - Denby, SD
  • Average rainfall days in September: 6.1 days

The month with the highest number of rainy days is May (13.1 days).
The months with the least rainy days are February and December (2.5 days).

Average snowfall in September
Denby, SD

Average snowfall in September - Denby, SD
  • Average snowfall in September: 0.04"

The month with the highest snowfall is February (4.02").
The months with the least snowfall are June, July and August (0").

Average snowfall days in September
Denby, SD

Average snowfall days in September - Denby, SD
  • Average snowfall days in September: 0.1 days

The month with the highest number of snowfall days is February (11.5 days).
The months with the least snowfall days are June, July and August (0 days).

Average daylight in September /
Average sunshine in September
Denby, SD

Average daylight in September / Average sunshine in September - Denby, SD
  • Average daylight in September: 12h and 3min

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: 10h and 1min

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 12min).

Average sunshine days in September
Denby, SD

Average sunshine days in September - Denby, SD
  • Average sunshine days in September: 22.8 days

The month with the most sunshine days is September (22.8 days).
The month with the least sunshine days is April (13.2 days).

Average UV index in September
Denby, SD

Average UV index in September - Denby, SD
  • Average UV index in September: 4

The month with the highest UV index is July (UV index 7).
The months with the lowest UV index are January, February, November and December (UV index 2).

Average cloud cover in September
Denby, SD

Average cloud cover in September - Denby, SD
  • Average cloud cover in September: 19

The month with the most cloud cover is February (Cloud cover 44).
The month with the least cloud cover is August (Cloud cover 16).

Average visibility in September
Denby, SD

Average visibility in September - Denby, 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).

Denby, South Dakota, USA

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