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Portland Weather by Month
Average temperatures, rainfall and humidity for Portland, United States, month by month, built from OpenWeather's historical records. Use it to see what a typical Portland month looks like before you travel — then check the live Portland forecast for the days ahead.
Warmest month
August
30°C average high
Coolest month
January
3°C average low
Wettest month
December
164 mm of rain
Driest month
July
12 mm of rain
Average temperature and rainfall in Portland by month
Averages of the daily highs and lows recorded in each month, with total rainfall, mean humidity and mean wind speed.
| Month | Avg high | Avg low | Record low / high | Rainfall | Humidity | Wind |
|---|---|---|---|---|---|---|
| January | 9°C | 3°C | -10°C / 16°C | 125 mm | 83% | 12 km/h |
| February | 10°C | 3°C | -8°C / 19°C | 107 mm | 82% | 11 km/h |
| March | 14°C | 5°C | -5°C / 28°C | 114 mm | 77% | 11 km/h |
| April | 17°C | 6°C | 0°C / 31°C | 88 mm | 70% | 10 km/h |
| May | 22°C | 10°C | 1°C / 33°C | 56 mm | 68% | 9 km/h |
| June | 25°C | 12°C | 6°C / 45°C | 47 mm | 65% | 9 km/h |
| July | 29°C | 14°C | 8°C / 39°C | 12 mm | 61% | 9 km/h |
| August | 30°C | 15°C | 8°C / 41°C | 16 mm | 63% | 8 km/h |
| September | 25°C | 13°C | 5°C / 37°C | 69 mm | 70% | 8 km/h |
| October | 18°C | 8°C | -2°C / 30°C | 102 mm | 79% | 8 km/h |
| November | 12°C | 6°C | -7°C / 21°C | 129 mm | 83% | 11 km/h |
| December | 8°C | 3°C | -11°C / 18°C | 164 mm | 85% | 12 km/h |
Best time to visit Portland
The most comfortable time to visit Portland is generally May to June and September, balancing mild daytime temperatures against the driest stretch of the year. The city has strongly marked seasons and rain concentrates around December, totalling about 1030 mm a year.
Travellers who prefer heat should aim for August, when highs average 30°C. December is the month to avoid if rain would spoil your plans — it averages 164 mm, roughly 14× the rainfall of July.
Source: OpenWeather historical and statistical weather data. Values are long-term averages, not a forecast — see the Portland forecast for what is happening now.