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September Weather in Coos Bay, United States

Last updated: June 24, 2025

In September, the average temperature in Coos Bay, United States is a comfortable 15°C (60°F). You can expect cooler nights, with minimum temperatures dropping to 8°C (47°F), while daytime highs can reach up to 30°C (87°F). During this month, the region receives about 48 mm (1.9 in) of precipitation over approximately 6 days, contributing to an average humidity of 66%.

September Temperature in Coos Bay

In September in Coos Bay, the average temperature is 15°C (60°F). Maximum temperatures can reach 30°C (87°F), while minimums can drop to as low as 8°C (47°F). This makes it a great time for travelers to enjoy mild weather while exploring outdoor attractions.

September Weather in Coos Bay: Daily Temperature Highs, Lows, and Averages

The chart illustrates September temperature patterns in Coos Bay, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In Coos Bay, September typically has an average temperature of 15°C (60°F), with highs reaching up to 30°C (87°F) and lows dropping to around 8°C (47°F).
JanFebMarAprMayJunJulAugSepOctNovDec474547505458606160555047
Data source: Temperature data for Coos Bay generated using information from the Copernicus Climate Change Service.
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The average of daily temperatures (24 hours) calculated across all days in the month.

September Precipitation in Coos Bay

In Coos Bay in September, the precipitation amount is 48 mm (1.9 in) distributed over 6 days.

September Precipitation Trends in Coos Bay

The chart displays monthly precipitation patterns in Coos Bay, 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 Coos Bay, September typically receives around 48 mm (1.9 inches) of precipitation spread over approximately 6 days.
JanFebMarAprMayJunJulAugSepOctNovDec1922201491185937364870150204
Data source: Precipitation data for September generated using information from the Copernicus Climate Change Service.
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September Humidity in Coos Bay

In Coos Bay in September humidity is 66%. With an average temperature of 15°C (60°F), this humidity feels like a warm embrace, creating a slightly sticky atmosphere that encourages travelers to dress comfortably and stay hydrated as they explore.

September Average Humidity in Coos Bay

This chart illustrates the average monthly humidity levels in Coos Bay, 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 Coos Bay is approximately 66%, offering insight into how humid the weather typically is during this month.
JanFebMarAprMayJunJulAugSepOctNovDec84%85%86%83%83%83%78%67%66%77%87%87%
Data source: Humidity data for September generated using information from the Copernicus Climate Change Service.

September UV Index in Coos Bay

In Coos Bay 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 Coos Bay.

Maximum UV Index Levels in Coos Bay for September

The chart shows the monthly maximum UV Index (UVI) for Coos Bay 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 Coos Bay typically reaches 8, which falls under the very high exposure category.
JanFebMarAprMayJunJulAugSepOctNovDec246710101098532
Data source: Coos Bay 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 Coos Bay Compares to Other Months

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

This table compares monthly weather conditions in Coos Bay, showing how September’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
 TemperaturePrecipitationHumidityUV
January Weather8°C (47°F)192 mm (7.6 inches)84%low
February Weather7°C (46°F)220 mm (8.7 inches)85%moderate
March Weather8°C (47°F)149 mm (5.9 inches)86%high
April Weather10°C (50°F)118 mm (4.6 inches)83%high
May Weather12°C (54°F)59 mm (2.3 inches)83%very high
June Weather14°C (58°F)37 mm (1.4 inches)83%very high
July Weather16°C (60°F)3 mm (0.1 inches)78%very high
August Weather16°C (61°F)6 mm (0.2 inches)67%very high
September Weather15°C (60°F)48 mm (1.9 inches)66%very high
October Weather13°C (55°F)70 mm (2.7 inches)77%moderate
November Weather10°C (51°F)150 mm (5.9 inches)87%moderate
December Weather8°C (47°F)204 mm (8.0 inches)87%low

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