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September Weather in Oregon, United States

Last updated: June 24, 2025

In Oregon, United States, the average temperature in September hovers around 20°C (67°F), but be prepared for variability—minimums can drop to 2°C (37°F) while maximums can soar to 34°C (93°F). This month sees an average precipitation of 120 mm (4.7 in), spread across about 10 days, and the air tends to be quite humid, with levels reaching 80%.

September Temperature in Oregon

In September in Oregon, the average temperature is 20°C (67°F). Maximum temperatures can reach 34°C (93°F), while minimums can drop as low as 2°C (37°F). It's advisable to pack layers and be prepared for both warm days and cooler nights while traveling.

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

The chart illustrates September temperature patterns in Oregon, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In Oregon, September typically has an average temperature of 20°C (67°F), with highs reaching up to 34°C (93°F) and lows dropping to around 2°C (37°F).
JanFebMarAprMayJunJulAugSepOctNovDec232539486172757367533832
Data source: Temperature data for Oregon 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 Oregon

In Oregon in September, the precipitation amount is 120 mm (4.7 in) spread over a duration of 10 days.

September Precipitation Trends in Oregon

The chart displays monthly precipitation patterns in Oregon, 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 Oregon, September typically receives around 120 mm (4.7 inches) of precipitation spread over approximately 10 days.
JanFebMarAprMayJunJulAugSepOctNovDec60567910915712178771201164951
Data source: Precipitation data for September generated using information from the Copernicus Climate Change Service.
Choose your preferred precipitation unit

September Humidity in Oregon

In Oregon in September, humidity is 80%. With an average temperature of 20°C (67°F), this humidity feels like a warm embrace that can make outdoor activities feel sticky and heavy, potentially draining your energy as you explore.

September Average Humidity in Oregon

This chart illustrates the average monthly humidity levels in Oregon, 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 Oregon is approximately 80%, offering insight into how humid the weather typically is during this month.
JanFebMarAprMayJunJulAugSepOctNovDec82%83%84%85%79%82%80%81%80%82%88%84%
Data source: Humidity data for September generated using information from the Copernicus Climate Change Service.

September UV Index in Oregon

In Oregon 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 Oregon.

Maximum UV Index Levels in Oregon for September

The chart shows the monthly maximum UV Index (UVI) for Oregon 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 Oregon typically reaches 8, which falls under the very high exposure category.
JanFebMarAprMayJunJulAugSepOctNovDec34689101098632
Data source: Oregon 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 Oregon Compares to Other Months

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

This table compares monthly weather conditions in Oregon, showing how September’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
 TemperaturePrecipitationHumidityUV
January Weather-5°C (23°F)60 mm (2.4 inches)82%moderate
February Weather-4°C (26°F)56 mm (2.2 inches)83%moderate
March Weather4°C (39°F)79 mm (3.1 inches)84%high
April Weather9°C (48°F)109 mm (4.3 inches)85%very high
May Weather16°C (61°F)156 mm (6.2 inches)79%very high
June Weather22°C (72°F)121 mm (4.8 inches)82%very high
July Weather24°C (76°F)78 mm (3.1 inches)80%very high
August Weather23°C (73°F)77 mm (3.0 inches)81%very high
September Weather20°C (67°F)120 mm (4.7 inches)80%very high
October Weather12°C (54°F)116 mm (4.6 inches)82%high
November Weather3°C (38°F)49 mm (1.9 inches)88%moderate
December Weather0°C (32°F)51 mm (2.0 inches)84%low

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