The climate of Portland can be defined as oceanic with Mediterranean influences. In fact, winter is mild enough, but not as in the Mediterranean climate, and rainfall is frequent for many months a year, but summer is hot and sunny, albeit with quite cool nights.
Portland is the largest city of Oregon and is located 100 km (60 mi) away from the Pacific coast, on the confluence of the Willamette and Columbia rivers, beyond which lies the city of Vancouver, in the state of Washington. We are in northwestern United States.
In winter, fog can form at night and in the early morning. On the coldest nights of the year, the temperature generally drops to -7/-8 °C (18/19 °F), but sometimes it can also drop below. In 1989, it went down to -13 °C (8.5 °F), and back in 1950, to as low as -19 °C (-2 °F). Sometimes it can snow, although heavy snowfalls are rare. On average, 11 cm (4.3 in) of snow fall per year.
In summer, there may be heat waves that last a few days. On the hottest days of the year, the temperature usually reaches 37/38 °C (99/100 °F). In 1981, it reached 41.6 °C (107 °F).
Not far from Portland there are two volcanoes: 75 km (45 mi) to the southeast is Mount Hood, which is the highest peak in Oregon with its 3,425 meters (11,237 ft), while 75 km (45 mi) to the northeast, in the state of Washigton, we find Mount St. Helens, 2,549 meters (8,363 ft) high and famous for the 1980 eruption.
The average temperature of the coldest month (December) is of 4.7 °C (40 °F), that of the warmest month (August) is of 20.9 °C (70 °F). Here are the average temperatures.

Precipitation amounts to 915 millimeters (36 inches) per year: so, it is at an intermediate level. However, as in Seattle, excluding summer, there may be a few consecutive days characterized by continuous drizzle. Rainfall ranges from 15 mm (0.6 in) in the driest months (July, August) to 145 mm (5.7 in) in the wettest (November). Here is the average precipitation.

On average, there are around 2,340 sunshine hours per year. The sun shines 23% of the time in December and 70% of the time in July (in Seattle, a little further north, the average goes from 20% in December to 65% in July). Here are the average sunshine hours per day.

Best Time

The best time in Portland is from mid-May to late September. The driest and sunniest period is generally from mid-June to early September, but it can sometimes get very hot, especially in July and August. You can therefore go from mid-May to mid-June and in the month of September.

Back to Oregon.