September weather forecast
North Sioux City, SD

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Weather in September

September in North Sioux City signals the advent of autumn with temperatures beginning to fall compared to August. The cooler climate of October is hinted at throughout September, with temperatures slowly declining. Days start becoming shorter and cloud cover increases slightly. Despite these changes, rain showers remain frequent, though less so than in the wet months of June and July. Notably, September has a significant decrease in UV index, decreasing to a level of 5 from the high of 6 in the summer.

Temperature

The onset of September is marked by a minor decrease in temperature, transitioning from a warm 82°F (27.8°C) in August to a still moderately hot 76.1°F (24.5°C). In September, the temperature drops to an average of 55°F (12.8°C) at night.

Humidity

In September, the average relative humidity is 70%.

Rainfall

In September, in North Sioux City, the rain falls for 11.8 days. Throughout September, 1.93" (49mm) of precipitation is accumulated. In North Sioux City, South Dakota, during the entire year, the rain falls for 122 days and collects up to 21.61" (549mm) of precipitation.

Snowfall

In North Sioux City, snow does not fall in June through September.

Daylight

The average length of the day in September is 12h and 28min.
On the first day of the month, sunrise is at 6:51 am and sunset at 7:59 pm. On the last day of September, sunrise is at 7:22 am and sunset at 7:08 pm CDT.

Sunshine

In North Sioux City, the average sunshine in September is 8.8h.

UV index

In North Sioux City, the average daily maximum UV index in September is 5. A UV Index value of 3 to 5 symbolizes a medium vulnerability from exposure to the Sun's UV rays for the ordinary person.
Note: A daily maximum UV index of 5 in September translates into the following instructions:
Be mindful. Those with pale skin might receive burns in fewer than 30 minutes. The intensity of the Sun's UV radiation during midday suggests reducing time spent outdoors. Select sunglasses that boast both UVA and UVB protection to limit the adverse effects of the sun on the eyes.
Updated: Feb 14, 2024
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate

Frequently asked questions

What is the average September temperature in North Sioux City?

In September, in North Sioux City, the average high-temperature is 76.1°F (24.5°C), and the average low-temperature is 55°F (12.8°C). In August, the average heat index (a.k.a. 'apparent temperature', 'real feel'), which combines relative humidity and air temperature, is appraised at 87.8°F (31°C).

What is the average humidity in September in North Sioux City?

In September, the average relative humidity is 70%.

How many days does it rain in September in North Sioux City?

In North Sioux City, in September, it is raining for 11.8 days, with typically 1.93" (49mm) of accumulated precipitation.

When it does not snow in North Sioux City?

June through September are months without snowfall in North Sioux City.

Does it snow in North Sioux City in September?

In North Sioux City, South Dakota, in September, it doesn't snow. In October, it regularly snows.

What is the average length of the day in September in North Sioux City?

In September, the average day length is 12h and 28min.

When is the sunrise / sunset in September in North Sioux City?

In September, on the first day of the month, sunrise is at 6:51 am and sunset at 7:59 pm. On the last day of the month, in North Sioux City, sunrise is at 7:22 am and sunset at 7:08 pm CDT.

How many hours of sunshine does North Sioux City have in September?

The average sunshine duration in September in North Sioux City is 8.8h.

What is the UV index intensity in September in North Sioux City?

In North Sioux City, the average daily maximum UV index in September is 5. A UV Index estimate of 3 to 5 represents a moderate vulnerability from unsafe exposure to Sun's UV rays.
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
North Sioux City, SD

Average temperature in September - North Sioux City, 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
North Sioux City, SD

Average pressure in September - North Sioux City, 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
North Sioux City, SD

Average wind speed in September - North Sioux City, 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
North Sioux City, SD

Average humidity in September - North Sioux City, 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
North Sioux City, SD

Average rainfall in September - North Sioux City, 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
North Sioux City, SD

Average rainfall days in September - North Sioux City, 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
North Sioux City, SD

Average snowfall in September - North Sioux City, 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
North Sioux City, SD

Average snowfall days in September - North Sioux City, 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
North Sioux City, SD

Average daylight in September / Average sunshine in September - North Sioux City, 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: 8h and 5min

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
North Sioux City, SD

Average sunshine days in September - North Sioux City, 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
North Sioux City, SD

Average UV index in September - North Sioux City, 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
North Sioux City, SD

Average cloud cover in September - North Sioux City, 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
North Sioux City, SD

Average visibility in September - North Sioux 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).

North Sioux City, South Dakota, USA

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