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September Weather in Portland, Australia

Last updated: August 22, 2025

The average temperature in Portland, Australia during September is a pleasant 12°C (54°F). Expect lows of around 6°C (42°F) and highs reaching 24°C (75°F). With an average precipitation amount of 86 mm (3.4 in) spread over 13 days, it's wise to keep an umbrella handy. Additionally, the average humidity sits at a comfortable 76%, creating a refreshing atmosphere throughout the month.

September Temperature in Portland

In September in Portland, the average temperature is 12°C (54°F). The maximum can reach up to 24°C (75°F), while the minimum can drop to as low as 6°C (42°F). It's a great time to explore Portland as the mild weather is perfect for outdoor activities and sightseeing.

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

The chart illustrates September temperature patterns in Portland, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In Portland, September typically has an average temperature of 12°C (54°F), with highs reaching up to 24°C (75°F) and lows dropping to around 6°C (42°F).
JanFebMarAprMayJunJulAugSepOctNovDec646363595653525253555861
Data source: Temperature data for Portland 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 Portland

In Portland, in September, the precipitation amount is 86 mm (3.4 in) over the course of 13 days.

September Precipitation Trends in Portland

The chart displays monthly precipitation patterns in Portland, 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 Portland, September typically receives around 86 mm (3.4 inches) of precipitation spread over approximately 13 days.
JanFebMarAprMayJunJulAugSepOctNovDec32313652928112211386756844
Data source: Precipitation data for September generated using information from the Copernicus Climate Change Service.
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September Humidity in Portland

In Portland in September, humidity is 76%. With an average temperature of 12°C (54°F), this humidity feels like a heavy blanket enveloping you, making outdoor activities a bit uncomfortable and requiring frequent hydration while exploring.

September Average Humidity in Portland

This chart illustrates the average monthly humidity levels in Portland, 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 Portland is approximately 76%, offering insight into how humid the weather typically is during this month.
JanFebMarAprMayJunJulAugSepOctNovDec76%75%76%76%79%78%78%77%77%76%76%76%
Data source: Humidity data for September generated using information from the Copernicus Climate Change Service.

September UV Index in Portland

In Portland 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 Portland.

Maximum UV Index Levels in Portland for September

The chart shows the monthly maximum UV Index (UVI) for Portland 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 Portland typically reaches 7, which falls under the high exposure category.
JanFebMarAprMayJunJulAugSepOctNovDec13121074334791114
Data source: Portland 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 Portland Compares to Other Months

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

This table compares monthly weather conditions in Portland, showing how September’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
 TemperaturePrecipitationHumidityUV
January Weather18°C (64°F)32 mm (1.3 inches)76%extreme
February Weather17°C (63°F)31 mm (1.2 inches)75%extreme
March Weather17°C (63°F)35 mm (1.4 inches)76%very high
April Weather15°C (60°F)51 mm (2.0 inches)76%high
May Weather13°C (56°F)92 mm (3.6 inches)79%moderate
June Weather11°C (53°F)81 mm (3.2 inches)78%moderate
July Weather11°C (52°F)122 mm (4.8 inches)78%moderate
August Weather11°C (52°F)113 mm (4.4 inches)77%moderate
September Weather12°C (54°F)86 mm (3.4 inches)76%high
October Weather13°C (56°F)74 mm (2.9 inches)76%very high
November Weather15°C (59°F)68 mm (2.7 inches)76%extreme
December Weather16°C (61°F)44 mm (1.7 inches)76%extreme

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