September Weather in Williston, United States

Last updated: June 24, 2025

In September, the average temperature in Williston, United States hovers around 25°C (78°F). You can expect a comfortable range, with minimums dipping to 11°C (52°F) and maximums reaching up to 37°C (100°F). Precipitation is moderate, totaling 78 mm (3.1 in) over about 8 days, while humidity stays high at an average of 83%.

September Temperature in Williston

In September in Williston, the average temperature is 25°C (78°F). Maximums can reach 37°C (100°F), while minimums can dip as low as 11°C (52°F). This variability makes it essential to pack accordingly for your travels.

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 25°C (78°F), with highs reaching up to 37°C (100°F) and lows dropping to around 11°C (52°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 total precipitation amount is 78 mm (3.1 in) over the course of 8 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 78 mm (3.1 inches) of precipitation spread over approximately 8 days.

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

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Millimeters (mm) Inches (in)

September Humidity in Williston

In Williston in September, humidity is 83%. With an average temperature of 25°C (78°F), this humidity feels like stepping into a warm, damp embrace, making travel sticky and exhausting, as each movement can leave you drenched in sweat.

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 83%, 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 9, which corresponds to a very high Exposure Category. The time to burn is just 15 minutes, so it's essential to take precautions. For 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 9, which falls under the very 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	9°C (49°F)	88 mm (3.4 inches)	86%	moderate
February Weather	12°C (54°F)	110 mm (4.3 inches)	81%	high
March Weather	15°C (59°F)	81 mm (3.2 inches)	81%	very high
April Weather	18°C (66°F)	117 mm (4.6 inches)	79%	very high
May Weather	23°C (74°F)	102 mm (4.0 inches)	75%	extreme
June Weather	26°C (79°F)	111 mm (4.4 inches)	75%	extreme
July Weather	28°C (82°F)	143 mm (5.6 inches)	80%	extreme
August Weather	27°C (81°F)	144 mm (5.7 inches)	81%	extreme
September Weather	25°C (78°F)	78 mm (3.1 inches)	83%	very high
October Weather	21°C (69°F)	78 mm (3.1 inches)	78%	very high
November Weather	13°C (55°F)	60 mm (2.4 inches)	85%	high
December Weather	11°C (51°F)	122 mm (4.8 inches)	87%	moderate