September Weather in Union, United States

Last updated: June 24, 2025

In Union, United States, the average temperature in September is a pleasant 21°C (71°F), with minimums dipping to 7°C (45°F) and maximums soaring to 35°C (95°F). Expect 87 mm (3.4 in) of precipitation over about 7 days, while the average humidity hovers around 73%.

September Temperature in Union

In September in Union, the average temperature is 21°C (71°F). The maximum can reach 35°C (95°F), while the minimum can drop to as low as 7°C (45°F). This makes Union an ideal destination for travelers looking to enjoy a warm climate with refreshing cooler evenings.

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 21°C (71°F), with highs reaching up to 35°C (95°F) and lows dropping to around 7°C (45°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 87 mm (3.4 in) over a span of 7 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 87 mm (3.4 inches) of precipitation spread over approximately 7 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 73%. With an average temperature of 21°C (71°F), this humidity feels like a warm, enveloping blanket that can make outdoor activities a bit uncomfortable, but with proper hydration and breaks in the shade, it’s still manageable for traveling.

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 73%, 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 8, which corresponds to a very high Exposure Category. This means that the time to burn is only 15 minutes. For more detailed information, you can refer to 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 8, 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)	80 mm (3.1 inches)	88%	moderate
February Weather	3°C (38°F)	110 mm (4.3 inches)	88%	moderate
March Weather	7°C (46°F)	135 mm (5.3 inches)	87%	high
April Weather	12°C (55°F)	125 mm (4.9 inches)	85%	very high
May Weather	19°C (66°F)	126 mm (4.9 inches)	81%	very high
June Weather	23°C (74°F)	146 mm (5.7 inches)	82%	very high
July Weather	25°C (78°F)	113 mm (4.5 inches)	81%	very high
August Weather	24°C (75°F)	95 mm (3.7 inches)	73%	very high
September Weather	21°C (71°F)	87 mm (3.4 inches)	73%	very high
October Weather	15°C (59°F)	98 mm (3.9 inches)	78%	high
November Weather	7°C (44°F)	93 mm (3.7 inches)	89%	moderate
December Weather	4°C (39°F)	109 mm (4.3 inches)	87%	moderate