September Weather in Union, United States

Last updated: June 24, 2025

In September, the average temperature in Union, United States is a pleasant 19°C (67°F). Visitors can expect a minimum temperature of 3°C (38°F) and a maximum of 33°C (92°F), offering a delightful range for outdoor activities. Rainfall is also part of the picture, with an average precipitation of 101 mm (4.0 in) over approximately 10 days. The air tends to be quite humid, with an average humidity level of 68%, making for an intriguing climate experience.

September Temperature in Union

In September in Union, the average temperature is 19°C (67°F). Maximum temperatures can reach 33°C (92°F), while minimums can dip as low as 3°C (38°F). It's a good idea to pack layers and be prepared for both warm days and chilly nights while traveling.

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

The chart illustrates September temperature patterns in Union, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In Union, September typically has an average temperature of 19°C (67°F), with highs reaching up to 33°C (92°F) and lows dropping to around 3°C (38°F).

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

September Precipitation in Union

In Union in September, the precipitation amount is 101 mm (4.0 in) spread over the course of 10 days.

September Precipitation Trends in Union

The chart displays monthly precipitation patterns in Union, 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 Union, September typically receives around 101 mm (4.0 inches) of precipitation spread over approximately 10 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 Union

In Union in September, humidity is 68%. With an average temperature of 19°C (67°F), this humidity feels like a warm, enveloping blanket, making travel pleasant yet slightly muggy, which can be refreshing while exploring but may require occasional breaks to stay comfortable.

September Average Humidity in Union

This chart illustrates the average monthly humidity levels in Union, 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 Union 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 Union

In Union 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 Union.

Maximum UV Index Levels in Union for September

The chart shows the monthly maximum UV Index (UVI) for Union 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 Union typically reaches 9, which falls under the very high exposure category.

Data source: Union 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 Union Compares to Other Months

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

This table compares monthly weather conditions in Union, 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)	74 mm (2.9 inches)	87%	moderate
February Weather	4°C (40°F)	124 mm (4.9 inches)	87%	high
March Weather	7°C (44°F)	92 mm (3.6 inches)	86%	very high
April Weather	12°C (53°F)	113 mm (4.5 inches)	84%	very high
May Weather	17°C (62°F)	131 mm (5.2 inches)	83%	extreme
June Weather	20°C (69°F)	93 mm (3.7 inches)	83%	extreme
July Weather	23°C (73°F)	69 mm (2.7 inches)	79%	extreme
August Weather	22°C (72°F)	88 mm (3.5 inches)	66%	very high
September Weather	19°C (67°F)	101 mm (4.0 inches)	68%	very high
October Weather	14°C (57°F)	108 mm (4.2 inches)	78%	high
November Weather	6°C (43°F)	70 mm (2.7 inches)	89%	moderate
December Weather	3°C (39°F)	95 mm (3.7 inches)	86%	moderate