September Weather in Williston, United States

Last updated: June 24, 2025

In Williston, United States, the average temperature in September hovers around 15°C (58°F). During this time, you might experience a minimum chill of -4°C (26°F) and a scorching maximum of 34°C (93°F). With an average humidity of 65% and 59 mm (2.3 in) of precipitation spread over 5 days, it's a month of diverse weather experiences. Prepare for anything from chilly days to warm sunshine!

September Temperature in Williston

In September in Williston, the average temperature is 15°C (58°F). Maximum temperatures can reach up to 34°C (93°F), while minimum temperatures can dip as low as -4°C (26°F). It's advisable to pack for a wide range of weather conditions if you're traveling during this time.

September Weather in Williston: Daily Temperature Highs, Lows, and Averages

The chart illustrates September temperature patterns in Williston, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In Williston, September typically has an average temperature of 15°C (58°F), with highs reaching up to 34°C (93°F) and lows dropping to around -4°C (26°F).

Data source: Temperature data for Williston generated using information from the Copernicus Climate Change Service.

September Precipitation in Williston

In Williston in September, the precipitation amount is 59 mm (2.3 in) over the course of 5 days.

September Precipitation Trends in Williston

The chart displays monthly precipitation patterns in Williston, with values for each month alongside September’s data, which is highlighted for easy comparison. It shows the amount of precipitation, providing insights into how September’s conditions compare to those of other months. In Williston, September typically receives around 59 mm (2.3 inches) of precipitation spread over approximately 5 days.

Data source: Precipitation data for September generated using information from the Copernicus Climate Change Service.

Choose your preferred precipitation unit

Millimeters (mm) Inches (in)

September Humidity in Williston

In Williston in September, humidity is 65%. With an average temperature of 15°C (58°F), this humidity feels like a mild but slightly muggy experience for traveling, making it essential to stay hydrated and wear breathable clothing to fully enjoy the day.

September Average Humidity in Williston

This chart illustrates the average monthly humidity levels in Williston, with September’s data highlighted for easy comparison. It shows the fluctuation in humidity throughout the year, helping you understand how conditions vary by season. In September, average humidity in Williston is approximately 65%, offering insight into how humid the weather typically is during this month.

Data source: Humidity data for September generated using information from the Copernicus Climate Change Service.

September UV Index in Williston

In Williston in September, the maximum UV index is 7, which corresponds to the high Exposure Category. This means that the time to burn is approximately 25 minutes. For more detailed information, you can check the Hourly UV Index in Williston.

Maximum UV Index Levels in Williston for September

The chart shows the monthly maximum UV Index (UVI) for Williston in September, representing the highest UV radiation level. The UVI measures the intensity of ultraviolet radiation from the sun, indicating the potential risk of sunburn and UV-related health issues. In September, the maximum UV index in Williston typically reaches 7, which falls under the high exposure category.

Data source: Williston September UVI data generated using information from the Copernicus Climate Change Service.

UV Risk Categories

Extreme (11+): Avoid the sun, stay in shade.
Very High (8-10): Limit sun exposure.
High (6-7): Use SPF 30+ and protective clothing.
Moderate (3-5): Midday shade recommended.
Low (0-2): No protection needed.

How September Weather in Williston Compares to Other Months

Weather in Williston varies notably across the year, with each month offering distinct climate conditions. This page compares September’s weather to other months in Williston, focusing on differences in temperature, rainfall, humidity, and UV levels.

This table compares monthly weather conditions in Williston, showing how September’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
	Temperature	Precipitation	Humidity	UV
January Weather	-10°C (14°F)	11 mm (0.4 inches)	89%	low
February Weather	-12°C (11°F)	18 mm (0.7 inches)	92%	moderate
March Weather	-2°C (28°F)	23 mm (0.9 inches)	84%	moderate
April Weather	3°C (38°F)	28 mm (1.1 inches)	74%	very high
May Weather	12°C (55°F)	45 mm (1.8 inches)	73%	very high
June Weather	19°C (66°F)	74 mm (2.9 inches)	69%	very high
July Weather	22°C (71°F)	58 mm (2.3 inches)	76%	very high
August Weather	20°C (68°F)	44 mm (1.7 inches)	74%	very high
September Weather	15°C (58°F)	59 mm (2.3 inches)	65%	high
October Weather	5°C (42°F)	30 mm (1.2 inches)	71%	moderate
November Weather	-2°C (29°F)	19 mm (0.7 inches)	84%	low
December Weather	-7°C (20°F)	19 mm (0.8 inches)	92%	low