Last updated: June 24, 2025
In Williston, United States, the average temperature in September hovers around 16°C (62°F), but expect a range from a chilly 0°C (32°F) to a warm 32°C (89°F). With 71 mm (2.8 in) of precipitation spread over 9 days, it's a month where you might want to keep an umbrella handy. Additionally, the air carries an average humidity of 78%, making it a typically moist and inviting time of year.
In September in Williston, the average temperature is 16°C (62°F). Maximum can reach 32°C (89°F) and minimum can be as low as 0°C (32°F). This makes it a great time to visit, as you can enjoy warm days while being prepared for cooler evenings.
In Williston in September, the precipitation amount is 71 mm (2.8 in) spread over 9 days.
In Williston in September, humidity is 78%. With an average temperature of 16°C (62°F), this humidity feels like a warm blanket wrapping around you, making outdoor activities enjoyable yet slightly sticky. Travelers may find the weather pleasantly mild, though they'll appreciate having light, breathable clothing on hand to stay comfortable while exploring.
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.
UV Risk Categories
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.
| Temperature | Precipitation | Humidity | UV | |
|---|---|---|---|---|
| January Weather | -7°C (20°F) | 84 mm (3.3 inches) | 93% | low |
| February Weather | -5°C (23°F) | 81 mm (3.2 inches) | 92% | moderate |
| March Weather | -1°C (30°F) | 77 mm (3.0 inches) | 86% | moderate |
| April Weather | 6°C (43°F) | 109 mm (4.3 inches) | 85% | very high |
| May Weather | 13°C (56°F) | 91 mm (3.6 inches) | 80% | very high |
| June Weather | 18°C (65°F) | 97 mm (3.8 inches) | 74% | very high |
| July Weather | 21°C (71°F) | 108 mm (4.2 inches) | 76% | very high |
| August Weather | 20°C (69°F) | 87 mm (3.4 inches) | 75% | very high |
| September Weather | 16°C (62°F) | 71 mm (2.8 inches) | 78% | high |
| October Weather | 10°C (50°F) | 152 mm (6.0 inches) | 86% | moderate |
| November Weather | 2°C (35°F) | 112 mm (4.4 inches) | 88% | moderate |
| December Weather | -3°C (26°F) | 80 mm (3.2 inches) | 89% | low |