September Weather in Sequim, United States

Last updated: June 24, 2025

In Sequim, United States, the average temperature in September is a mild 13°C (56°F), with minimums dropping to 5°C (41°F) and maximums rising to 25°C (77°F). Expect a fair amount of rainfall as well, with 122 mm (4.8 in) over 15 days. The air tends to be quite humid, averaging around 74%.

September Temperature in Sequim

In September in Sequim, the average temperature is 13°C (56°F). Maximums can reach 25°C (77°F), while minimums can drop as low as 5°C (41°F). This mild weather makes Sequim an appealing destination for travelers looking to explore comfortably.

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

The chart illustrates September temperature patterns in Sequim, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In Sequim, September typically has an average temperature of 13°C (56°F), with highs reaching up to 25°C (77°F) and lows dropping to around 5°C (41°F).

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

September Precipitation in Sequim

In Sequim in September, the precipitation amount is 122 mm (4.8 in) over a span of 15 days.

September Precipitation Trends in Sequim

The chart displays monthly precipitation patterns in Sequim, 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 Sequim, September typically receives around 122 mm (4.8 inches) of precipitation spread over approximately 15 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 Sequim

In Sequim in September humidity is 74%. With an average temperature of 13°C (56°F), this humidity feels like a damp chill that can make outdoor activities uncomfortable, especially for travelers unaccustomed to such conditions.

September Average Humidity in Sequim

This chart illustrates the average monthly humidity levels in Sequim, 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 Sequim is approximately 74%, 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 Sequim

In Sequim 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 Sequim.

Maximum UV Index Levels in Sequim for September

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

Data source: Sequim 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 Sequim Compares to Other Months

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

This table compares monthly weather conditions in Sequim, showing how September’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
	Temperature	Precipitation	Humidity	UV
January Weather	3°C (38°F)	182 mm (7.2 inches)	86%	low
February Weather	2°C (36°F)	150 mm (5.9 inches)	84%	moderate
March Weather	4°C (40°F)	128 mm (5.1 inches)	85%	moderate
April Weather	7°C (44°F)	119 mm (4.7 inches)	83%	high
May Weather	11°C (51°F)	93 mm (3.7 inches)	84%	very high
June Weather	13°C (56°F)	118 mm (4.6 inches)	84%	very high
July Weather	15°C (60°F)	49 mm (1.9 inches)	82%	very high
August Weather	16°C (61°F)	45 mm (1.8 inches)	73%	very high
September Weather	13°C (56°F)	122 mm (4.8 inches)	74%	high
October Weather	9°C (48°F)	143 mm (5.6 inches)	83%	moderate
November Weather	6°C (42°F)	199 mm (7.8 inches)	86%	moderate
December Weather	3°C (38°F)	193 mm (7.6 inches)	87%	low