Portland climate
Portland (Oregon, United States) has a warm-summer Mediterranean climate (Köppen Csb). The average temperature over the year is 12 °C54 °F, and about 1,484 mm58 in of precipitation falls in an average year.
Temperature by month
Precipitation by month
Portland climate table
| Month | High °C°F | Low °C°F | Mean °C°F | Precip. mmin |
|---|---|---|---|---|
| Jan | 847 | 236 | 541 | 2168.5 |
| Feb | 949 | 236 | 642 | 1445.7 |
| Mar | 1254 | 439 | 846 | 1787.0 |
| Apr | 1559 | 542 | 1050 | 1194.7 |
| May | 1966 | 947 | 1457 | 793.1 |
| Jun | 2272 | 1152 | 1762 | 552.2 |
| Jul | 2882 | 1356 | 2169 | 110.4 |
| Aug | 2984 | 1456 | 2170 | 190.8 |
| Sep | 2577 | 1152 | 1865 | 572.2 |
| Oct | 1763 | 846 | 1355 | 1375.4 |
| Nov | 1152 | 440 | 846 | 2178.6 |
| Dec | 745 | 235 | 540 | 2519.9 |
| Year | 2984 | 235 | 1254 | 1,48458 |
“Year” row: highest monthly high, lowest monthly low, annual mean and annual total.
| Month | Humid. | Cloud | Solar | Daylight |
|---|---|---|---|---|
| Jan | 92% | 79% | 1.2 | 9:04 |
| Feb | 89% | 75% | 2.1 | 10:19 |
| Mar | 87% | 78% | 3.0 | 11:47 |
| Apr | 84% | 75% | 4.3 | 13:28 |
| May | 82% | 68% | 5.4 | 14:53 |
| Jun | 80% | 62% | 6.0 | 15:40 |
| Jul | 70% | 39% | 6.8 | 15:21 |
| Aug | 65% | 40% | 5.8 | 14:06 |
| Sep | 68% | 47% | 4.3 | 12:28 |
| Oct | 80% | 63% | 2.6 | 10:50 |
| Nov | 89% | 77% | 1.4 | 9:25 |
| Dec | 92% | 81% | 1.0 | 8:43 |
Humid. = average relative humidity at 2 m; cloud = average cloud amount; solar = average daily solar energy reaching the ground in kWh/m² (all-sky); daylight in hours:minutes, calculated for the 15th of each month.
What the climate of Portland is like
The warmest month is August, with an average high of 29 °C84 °F and a low of 14 °C56 °F. The coldest is December, when highs average 7 °C45 °F and lows 2 °C35 °F. There is a clear seasonal cycle, with 16.7 °C30 °F between the average temperature of the warmest and the coolest month.
It is wet, with about 1,484 mm58 in of precipitation per year. The wettest three-month stretch is November–January, which brings 46% of the annual total. Months with less than 20 mm0.8 in on average: July and August. The wettest month is December (251 mm9.9 in), the driest is July (11 mm0.4 in).
Relative humidity ranges from 65% in August to 92% in December. The clearest skies (lowest average cloud amount, 39%) are typical of July. Average wind speed near the ground ranges from 2 km/h (2 mph) in May to 3 km/h (2 mph) in March. Daylight lasts from about 8.7 hours in December to 15.7 hours in June.
A lasting snow cover is typical in December and January, when the average snow depth in the reanalysis exceeds 10 cm (deepest in December, about 11 cm).
Best time to visit Portland
Based on these averages, the most comfortable months for sightseeing and outdoor activities are June–September: average highs of 22 °C72 °F to 29 °C84 °F with 11 mm0.4 in to 57 mm2.2 in of precipitation per month.
The most challenging month is December, which is cold, with average highs of 7 °C45 °F and very wet (251 mm9.9 in).
Comfort score: months are ranked by how close they come to an average high of 21–28 °C (70–82 °F), lows above 5 °C (41 °F), little precipitation and moderate humidity. The best-ranked months of each place are recommended, even where none meets all of these. These are general rules of thumb applied to long-term averages.
What to pack for Portland
- Winter (December–February) — highs 745 to 9 °C49 °F, lows around 2 °C35 °F, about 204 mm8.0 in of precipitation a month. Pack a warm coat, layers and closed shoes and a good rain jacket or umbrella and quick-drying shoes.
- Spring (March–May) — highs 1254 to 19 °C66 °F, lows 439 to 9 °C47 °F, about 125 mm4.9 in of precipitation a month. Pack long sleeves, a sweater and a medium jacket and an umbrella or light rain jacket.
- Summer (June–August) — highs 2272 to 29 °C84 °F, lows 1152 to 14 °C56 °F, about 28 mm1.1 in of precipitation a month. Pack light summer clothes such as T-shirts, shorts or light dresses and an extra layer for the cooler mornings and evenings.
- Autumn (September–November) — highs 1152 to 25 °C77 °F, lows 440 to 11 °C52 °F, about 137 mm5.4 in of precipitation a month. Pack long sleeves, a sweater and a medium jacket, an extra layer for the cooler mornings and evenings and an umbrella or light rain jacket.
How Portland compares
Compared with Seattle, about 233 km to the north, Portland is on average 1.2 °C2.1 °F warmer and receives 20% more precipitation (1,484 mm58 in vs 1,232 mm49 in). The difference is largest in August (2.7 °C4.9 °F warmer).
Of the 222 places in the United States covered by World Climates, Portland is the 153rd warmest by annual mean temperature and the 7th wettest by annual precipitation. See all of them on the United States climate page.
Places in other countries with the most similar temperature and rainfall pattern: Vancouver (Canada, Csb), Viseu (Portugal, Csa) and Surrey (Canada, Csb).
The same NASA POWER grid cell also contains Vancouver (pop. 196,442) and Gresham (pop. 110,553). Their long-term averages in this dataset are essentially the same as for Portland, so they do not have separate pages.
Nearby places
- Hillsboro 24 km · 11 °C52 °F · 1,495 mm59 in
- Salem 70 km · 11 °C53 °F · 1,370 mm54 in
- Eugene 167 km · 12 °C53 °F · 1,375 mm54 in
- Seattle 233 km · 11 °C52 °F · 1,232 mm49 in
- Everett 275 km · 11 °C52 °F · 1,253 mm49 in
- Tri-Cities 281 km · 14 °C57 °F · 278 mm11 in
- Victoria 328 km · 11 °C51 °F · 991 mm39 in
- Abbotsford 394 km · 10 °C50 °F · 1,403 mm55 in
Frequently asked questions
What is the warmest month in Portland?
August is the warmest month in Portland, with an average high of 29 °C (84 °F) and an average low of 14 °C (56 °F).
What is the coldest month in Portland?
December is the coldest month, with an average high of 7 °C (45 °F) and an average low of 2 °C (35 °F).
When does it rain the most in Portland?
December is the wettest month with about 251 mm (9.9 in) of precipitation; July is the driest with about 11 mm (0.4 in).
What is the best time to visit Portland?
Judging by long-term averages, the most comfortable months are June–September.
About this data
All figures are 25-year averages (January 2001 – December 2025) from the NASA POWER project. Temperature, humidity, wind and precipitation come from the MERRA-2 reanalysis (precipitation is the bias-corrected MERRA-2 product), cloud and solar values from CERES satellite data. They describe a grid cell of roughly 50–70 km, not a single weather station, so they can differ from airport records — most of all on coasts, in mountains and for rainfall. Average highs and lows are the monthly mean temperature plus/minus half of the average daily temperature range. Counts of rainy days are not part of this dataset.
The grid cell’s average elevation is 257 m, while Portland lies at about 12 m. Temperatures on this page were therefore adjusted by +1.6 °C2.9 °F using the standard lapse rate of 6.5 °C per 1,000 m.