Williston
North Dakota, USA
Long-term weather forecast
Long-term weather forecast

September weather forecast and climate
Williston, ND

September, the first month of the autumn, in Williston, is also an agreeable month, with average temperature fluctuating between 71.2°F (21.8°C) and 42.1°F (5.6°C).

Temperature

In Williston, the average high-temperature drops, from a warm 83.8°F (28.8°C) in August, to an agreeable 71.2°F (21.8°C). In Williston, North Dakota, in September, the average low-temperature is 42.1°F (5.6°C).

Humidity

In Williston, the average relative humidity in September is 61.1%.

Rainfall

In September, in Williston, the rain falls for 7.4 days. Throughout September, 1.1" (26.9mm) of precipitation is accumulated. In Williston, during the entire year, the rain falls for 96.5 days and collects up to 14.4" (364.9mm) of precipitation.

Snowfall

Months with snowfall are January through May, September through December. September is the first month it typically snows in Williston. Throughout September, in the average 0.1 snowfall days, it receives 0.2" (5.1mm) of snow. In Williston, during the entire year, snow falls for 41.2 days, and aggregates up to 45.3" (1150.6mm) of snow.

Daylight

The average length of the day is 12.6h.

Sunshine

In Williston, North Dakota, the average sunshine is 8.3h.

UV index

The average daily maximum UV index in Williston is 5. A UV Index estimate of 3 to 5 represents a medium health hazard from the exposure to the Sun's UV radiation for the ordinary person.
Note: In September, the average maximum UV index of 5 translate into the following recommendations:
Take precautions - Protection against sunburn is recommended. The solar radiation is most powerful near the mid-day, so the exposure to the direct Sun should be reduced accordingly. On bright days sunglasses that block both UVA and UVB rays should be worn. A hat with a wide brim is extremely helpful, as it can prevent roughly 50% of UV radiation from reaching the eyes. Caution! The reflection of snow can nearly double the intensity of the Sun's UV radiation.

What is the temperature in September in Williston?

In Williston, North Dakota, in September, the average high-temperature is 71.2°F (21.8°C), and the average low-temperature is 42.1°F (5.6°C).

What is the average humidity in September in Williston?

In Williston, North Dakota, the average relative humidity in September is 61.1%.

How much does it rain in Williston in September?

In Williston, in September, it is raining for 7.4 days, with typically 1.1" (26.9mm) of accumulated precipitation.

When does it start snowing in Williston?

September is the first month it typically snows in Williston. Throughout September, in the average 0.1 snowfall days, it receives 0.2" (5.1mm) of snow.

What is the average length of the day in September in Williston?

In Williston, the average length of the day in September is 12.6h.

How long on average sun shines in September in Williston?

In September, the average sunshine in Williston is 8.3h.

What is the UV index intensity in September in Williston?

In September, the average daily maximum UV index in Williston is 5. A UV Index of 3 to 5 symbolizes a moderate health threat from the exposure to the Sun's UV radiation.
Average temperature in September - Williston, ND
  • Average high temperature in September: 71.3°F

The warmest month (with the highest average high temperature) is July (84.4°F).
The month with the lowest average high temperature is January (21.9°F).

  • Average low temperature in September: 42.1°F

The month with the highest average low temperature is July (55.8°F).
The coldest month (with the lowest average low temperature) is January (0.1°F).

Average humidity in September - Williston, ND
  • Average humidity in September: 61.1%

The month with the highest relative humidity is December (77.1%).
The month with the lowest relative humidity is August (54.9%).

Average rainfall in September - Williston, ND
  • Average rainfall in September: 1.1"

Wettest months (with the highest rainfall) are June and July (2.5").
The driest month (with the lowest rainfall) is February (0.4").

Average rainfall days in September - Williston, ND
  • Average rainfall days in September: 7.4 days

The month with the highest number of rainy days is June (11.5 days).
The month with the lowest number of rainy days is February (6 days).

Average snowfall in September - Williston, ND
  • Average snowfall in September: 0.2"

The month with the highest snowfall is January (10").
Months with the lowest snowfall are June, July and August (0").

Average snowfall days in September - Williston, ND
  • Average snowfall days in September: 0.1 days

The month with the highest number of snowfall days is December (9.1 days).
Months with the lowest number of snowfall days are June, July and August (0 days).

Average daylight in September / Average sunshine in September - Williston, ND
  • Average daylight in September: 12.6h

The month with the longest days is June (Average daylight: 16h).
The month with shortest days is December (Average daylight: 8.4h).

  • Average sunshine in September: 8.3h

The month with most sunshine is July (Average sunshine: 11.8h).
The month with least sunshine is December (Average sunshine: 4h).

Average UV index in September - Williston, ND
  • Average UV index in September: 5

The month with the highest UV index is July (UV index 8).
Months with the lowest UV index are January, February, November and December (UV index 1).