Monthly climate guide
Portland weather in September
September in Portland is typically warm, with average daytime highs around 24°C (76°F) and night-time lows near 11°C (52°F). The month usually brings about 69 mm of rain (some rain) and is a mix of sun and cloud. Daytime highs are 4°C cooler than August and 8°C warmer than October.
What stands out in September
- In Portland, September is early autumn.
- Expect a big gap between day and night — about 13°C.
- Temperatures are falling — expect highs around 8°C lower by October.
- September is Portland's third warmest month.
Avg high
24°C
76°F
Avg low
11°C
52°F
Rainfall
69 mm
some rain
Humidity
68%
relative
Sky
50%
cloud · a mix of sun and cloud
Portland weather by month
Show the monthly averages as a table
| Month | Avg high | Avg low | Rain | Humidity | Cloud cover |
|---|---|---|---|---|---|
| January | 7°C / 45°F | 1°C / 34°F | 201 mm | 92% | 78% |
| February | 8°C / 46°F | 1°C / 34°F | 178 mm | 90% | 79% |
| March | 11°C / 51°F | 3°C / 37°F | 194 mm | 87% | 77% |
| April | 14°C / 57°F | 4°C / 40°F | 130 mm | 84% | 74% |
| May | 18°C / 64°F | 8°C / 46°F | 78 mm | 82% | 67% |
| June | 21°C / 70°F | 10°C / 49°F | 53 mm | 79% | 60% |
| July | 27°C / 80°F | 12°C / 53°F | 11 mm | 70% | 39% |
| August | 29°C / 84°F | 13°C / 55°F | 12 mm | 64% | 39% |
| September | 24°C / 76°F | 11°C / 52°F | 69 mm | 68% | 50% |
| October | 17°C / 62°F | 7°C / 45°F | 164 mm | 80% | 61% |
| November | 10°C / 50°F | 3°C / 38°F | 204 mm | 89% | 76% |
| December | 6°C / 43°F | 1°C / 33°F | 236 mm | 92% | 78% |
What to pack for September
- T-shirts plus a light layer for the evening
- Comfortable trainers or sandals for long walks
- An extra layer — evenings are noticeably cooler than afternoons
- A small travel umbrella, just in case
Is September a good time to visit Portland?
Compare the months in the chart above to find your ideal window.
Best time to visit Portland →Other United States cities in September
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Portland weather in September. WeatherCompare, 2026 (NASA POWER / ERA5, 2011–2020 monthly averages). https://weathercompare.eu/weather/usa/portland/september
<a href="https://weathercompare.eu/weather/usa/portland/september">Portland weather in September</a> (WeatherCompare)
<iframe src="https://weathercompare.eu/embed/usa/portland" width="300" height="160" style="border:0;border-radius:12px" loading="lazy" title="Portland weather in September"></iframe> <p style="font-size:12px"><a href="https://weathercompare.eu/weather/usa/portland/september">Portland weather in September</a> – WeatherCompare</p>
Portland in September: quick answers
Is September a good time to visit Portland?
September is a reasonable time for Portland: highs around 24°C and about 69 mm of rain, though not one of the three best months.
How warm is Portland in September?
Average highs are about 24°C (76°F) and average lows about 11°C (52°F), based on 10 years of daily data.
Does it rain a lot in Portland in September?
Portland typically gets around 69 mm of rain in September — some rain.
Figures are long-term averages for the area around Portland (NASA POWER / ERA5, 2011–2020), not a forecast for a specific year. For upcoming days, see the live multi-source forecast.