Portland weather in May
May in Portland: nice, a little rain, with clean air — an excellent time to visit.
#4 of 12 months in Portland · #161 of 604 destinations to visit in May · comfort 87/100 (tier A)
Updated June 2026 · climate normals from ERA5 reanalysis
Portland climate normals — May
| Daytime high | 21°C / 69°F | 😎 nice |
|---|---|---|
| Nighttime low | 9°C / 49°F | |
| Feels like (high) | 20°C / 68°F | |
| Rainfall | 68 mm / 2.7 in | 🌦 some rain |
| Rainy days | 12 days | |
| Humidity | 74% | 💧 humid |
| Dew point | 9°C / 47°F | |
| Sunshine | 10.7 h/day | |
| Daylight | 14.9 h | |
| Wind | 13 km/h / 8 mph | |
| Air quality (US AQI) | 34 | 🍃 good |
Monthly averages from ERA5 reanalysis. AQI is the mean US Air Quality Index for the month.
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Portland in May — FAQ
- Is May a good time to visit Portland?
- May in Portland: nice, a little rain, with clean air — an excellent time to visit. It ranks #4 of 12 months for Portland on SeasonMap's comfort score (87/100).
- What is the weather like in Portland in May?
- In May, Portland averages a daily high of 20.5°C and a low of 9.4°C, with about 67.7 mm of rain over roughly 11.8 rainy days.
- What is the air quality in Portland in May?
- Portland has a mean US Air Quality Index of about 34 in May.