September Weather in Jefferson, United States

Last updated: June 24, 2025

In September, the average temperature in Jefferson, United States hovers around 18°C (65°F). Temperatures can vary, with minimums dropping to 3°C (37°F) and maximums soaring to 29°C (84°F). Expect 126 mm (5.0 in) of precipitation over the course of 11 days, accompanied by an average humidity level of 68%.

September Temperature in Jefferson

In September in Jefferson, the average temperature is 18°C (65°F). Maximums can reach 29°C (84°F), and minimums can drop as low as 3°C (37°F). It's a great time for travelers to enjoy mild weather while exploring the sights, but pack both warm and light clothing to stay comfortable throughout the day.

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

The chart illustrates September temperature patterns in Jefferson, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In Jefferson, September typically has an average temperature of 18°C (65°F), with highs reaching up to 29°C (84°F) and lows dropping to around 3°C (37°F).

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

September Precipitation in Jefferson

In Jefferson in September, the total precipitation amount is 126 mm (5.0 in) spread over 11 days.

September Precipitation Trends in Jefferson

The chart displays monthly precipitation patterns in Jefferson, 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 Jefferson, September typically receives around 126 mm (5.0 inches) of precipitation spread over approximately 11 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 Jefferson

In Jefferson in September, humidity is 68%. With an average temperature of 18°C (65°F), this humidity feels like a warm, enveloping blanket, making travel somewhat sticky and requiring occasional breaks for refreshing hydration.

September Average Humidity in Jefferson

This chart illustrates the average monthly humidity levels in Jefferson, 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 Jefferson is approximately 68%, 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 Jefferson

In Jefferson in September, the maximum UV index reaches 10, which corresponds to a very high Exposure Category. With a time to burn of just 15 minutes, it's crucial to take precautions. For more detailed information, you can check the Hourly UV Index in Jefferson.

Maximum UV Index Levels in Jefferson for September

The chart shows the monthly maximum UV Index (UVI) for Jefferson 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 Jefferson typically reaches 10, which falls under the very high exposure category.

Data source: Jefferson 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 Jefferson Compares to Other Months

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

This table compares monthly weather conditions in Jefferson, showing how September’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
	Temperature	Precipitation	Humidity	UV
January Weather	1°C (34°F)	88 mm (3.5 inches)	87%	moderate
February Weather	4°C (40°F)	129 mm (5.1 inches)	87%	high
March Weather	7°C (44°F)	112 mm (4.4 inches)	86%	very high
April Weather	11°C (52°F)	143 mm (5.6 inches)	84%	extreme
May Weather	16°C (61°F)	140 mm (5.5 inches)	83%	extreme
June Weather	19°C (66°F)	132 mm (5.2 inches)	83%	extreme
July Weather	21°C (70°F)	103 mm (4.0 inches)	79%	extreme
August Weather	20°C (69°F)	133 mm (5.2 inches)	66%	extreme
September Weather	18°C (65°F)	126 mm (5.0 inches)	68%	very high
October Weather	13°C (56°F)	130 mm (5.1 inches)	78%	very high
November Weather	6°C (42°F)	76 mm (3.0 inches)	89%	high
December Weather	3°C (38°F)	107 mm (4.2 inches)	86%	moderate