Portland, Oregon weather in September

Averages from 2021–2025 (150 days of record).

Average high: 77°F
Average low: 55°F
Rainy days: ~6 per month
Total precipitation: 2.2 in
Warmest recorded: 98°F
Coldest recorded: 45°F

Expect September days in Portland, Oregon to top out around 77°F and cool to about 55°F overnight, with roughly 6 days of measurable rain across the month. In recent years September has ranged from 45°F to 98°F.

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Current Portland, Oregon forecast → · Historical data by Open-Meteo (ERA5).