September Weather in Union Gap, United States

Last updated: June 24, 2025

In September, the average temperature in Union Gap, United States hovers around 18°C (65°F). However, be prepared for a range of temperatures, with minimums dropping to 3°C (38°F) and peaks soaring to 38°C (100°F). Rainfall is modest, with an average precipitation of 12 mm (0.5 in) spread over just 3 days. Coupled with an average humidity of 62%, this season offers a delightful, if variable, climate.

September Temperature in Union Gap

In September in Union Gap, the average temperature is 18°C (65°F). Maximums can reach 38°C (100°F) and minimums can be as low as 3°C (38°F). Travelers should prepare for a range of temperatures, making it essential to pack both light clothing for warm days and warmer layers for the chilly nights.

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

The chart illustrates September temperature patterns in Union Gap, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In Union Gap, September typically has an average temperature of 18°C (65°F), with highs reaching up to 38°C (100°F) and lows dropping to around 3°C (38°F).

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

September Precipitation in Union Gap

In Union Gap in September, the precipitation amount is 12 mm (0.5 in) during a span of 3 days.

September Precipitation Trends in Union Gap

The chart displays monthly precipitation patterns in Union Gap, 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 Gap, September typically receives around 12 mm (0.5 inches) of precipitation spread over approximately 3 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 Gap

In Union Gap in September, humidity is 62%. With an average temperature of 18°C (65°F), this humidity feels like a warm embrace, making outdoor activities enjoyable yet mildly sticky, perfect for leisurely strolls but a bit challenging for vigorous excursions.

September Average Humidity in Union Gap

This chart illustrates the average monthly humidity levels in Union Gap, 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 Gap is approximately 62%, 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 Gap

In Union Gap 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 Union Gap.

Maximum UV Index Levels in Union Gap for September

The chart shows the monthly maximum UV Index (UVI) for Union Gap 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 Gap typically reaches 7, which falls under the high exposure category.

Data source: Union Gap 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 Gap Compares to Other Months

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

This table compares monthly weather conditions in Union Gap, showing how September’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
	Temperature	Precipitation	Humidity	UV
January Weather	0°C (33°F)	63 mm (2.5 inches)	86%	low
February Weather	1°C (34°F)	63 mm (2.5 inches)	86%	moderate
March Weather	6°C (42°F)	30 mm (1.2 inches)	87%	moderate
April Weather	10°C (51°F)	23 mm (0.9 inches)	84%	high
May Weather	16°C (62°F)	13 mm (0.5 inches)	81%	very high
June Weather	21°C (70°F)	6 mm (0.2 inches)	82%	very high
July Weather	25°C (77°F)	1 mm (0.0 inches)	79%	very high
August Weather	24°C (76°F)	4 mm (0.2 inches)	63%	very high
September Weather	18°C (65°F)	12 mm (0.5 inches)	62%	high
October Weather	10°C (51°F)	37 mm (1.4 inches)	83%	moderate
November Weather	4°C (40°F)	42 mm (1.7 inches)	89%	moderate
December Weather	1°C (34°F)	59 mm (2.3 inches)	88%	low