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September Weather in Corvallis, United States

Last updated: June 24, 2025

In September, the average temperature in Corvallis, United States hovers around 13°C (55°F). Temperatures can range from a chilly -6°C (22°F) to a warm 33°C (91°F). Expect about 34 mm (1.3 in) of precipitation spread over 6 days, while the average humidity level sits at a comfortable 67%.

September Temperature in Corvallis

In September in Corvallis, the average temperature is 13°C (55°F). The maximum can reach 33°C (91°F), and the minimum can be as low as -6°C (22°F). Travelers should be prepared for a wide range of temperatures and pack accordingly for both warm days and chilly nights.

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

The chart illustrates September temperature patterns in Corvallis, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In Corvallis, September typically has an average temperature of 13°C (55°F), with highs reaching up to 33°C (91°F) and lows dropping to around -6°C (22°F).
JanFebMarAprMayJunJulAugSepOctNovDec232232364756666455392922
Data source: Temperature data for Corvallis 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 Corvallis

In Corvallis in September, the total precipitation amount is 34 mm (1.3 in) spread over 6 days.

September Precipitation Trends in Corvallis

The chart displays monthly precipitation patterns in Corvallis, 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 Corvallis, September typically receives around 34 mm (1.3 inches) of precipitation spread over approximately 6 days.
JanFebMarAprMayJunJulAugSepOctNovDec439860697277172134655863
Data source: Precipitation data for September generated using information from the Copernicus Climate Change Service.
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September Humidity in Corvallis

In Corvallis in September humidity is 67%. With an average temperature of 13°C (55°F), this humidity feels like a chilly embrace, making travel a bit uncomfortable as the cool air settles in.

September Average Humidity in Corvallis

This chart illustrates the average monthly humidity levels in Corvallis, 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 Corvallis is approximately 67%, offering insight into how humid the weather typically is during this month.
JanFebMarAprMayJunJulAugSepOctNovDec93%92%89%85%80%78%77%66%67%77%89%95%
Data source: Humidity data for September generated using information from the Copernicus Climate Change Service.

September UV Index in Corvallis

In Corvallis 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 Corvallis.

Maximum UV Index Levels in Corvallis for September

The chart shows the monthly maximum UV Index (UVI) for Corvallis 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 Corvallis typically reaches 8, which falls under the very high exposure category.
JanFebMarAprMayJunJulAugSepOctNovDec346810101098532
Data source: Corvallis 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 Corvallis Compares to Other Months

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

This table compares monthly weather conditions in Corvallis, showing how September’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
 TemperaturePrecipitationHumidityUV
January Weather-5°C (23°F)43 mm (1.7 inches)93%moderate
February Weather-5°C (23°F)98 mm (3.9 inches)92%moderate
March Weather0°C (32°F)60 mm (2.4 inches)89%high
April Weather2°C (36°F)69 mm (2.7 inches)85%very high
May Weather8°C (47°F)72 mm (2.8 inches)80%very high
June Weather14°C (57°F)77 mm (3.0 inches)78%very high
July Weather19°C (66°F)17 mm (0.7 inches)77%very high
August Weather18°C (65°F)21 mm (0.8 inches)66%very high
September Weather13°C (55°F)34 mm (1.3 inches)67%very high
October Weather4°C (39°F)65 mm (2.5 inches)77%moderate
November Weather-1°C (30°F)58 mm (2.3 inches)89%moderate
December Weather-6°C (22°F)62 mm (2.5 inches)95%low

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