Portland, Oregon weather in May

Averages from 2021–2025 (155 days of record).

Average high: 66°F
Average low: 47°F
Rainy days: ~12 per month
Total precipitation: 3.5 in
Warmest recorded: 86°F
Coldest recorded: 34°F

Expect May days in Portland, Oregon to top out around 66°F and cool to about 47°F overnight, with roughly 12 days of measurable rain across the month. In recent years May has ranged from 34°F to 86°F.

Other months

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