Oregon, USA
Long-term weather forecast
Long-term weather forecast

Monthly weather forecast and Climate
Portland, OR

A colorful autumn view of the outline of Portland City, Oregon, with mountains in the distance
A colorful autumn view of the outline of Portland City, Oregon, with mountains in the distance
Portland experiences a temperate oceanic type of climate (Köppen climate classification Csb) with warm, dry summers and mildly cold, wet winters. It lies in the Pacific Northwest part of America, within the state of Oregon, at the confluence of the Columbia and Willamette rivers. The temperate latitudes, low altitude location, and distance from the Pacific Ocean mainly influence the climate of Portland.

Portland lies at an average altitude of 15 meters above sea level within the Willamette Valley. The terrain is mostly flat except for the foothills of the Tualatin Mountains on the western side of the city. The vegetation consists of a variety of trees such as fir, hemlock, red cedar, and broadleaf maple. The Oregon Coast Range and Portland's inland location reduce the influence of the Pacific Ocean on its climate.

Portland summers are warm, dry, and sunny with the average high temperature peaking at 81.1°F (27.3°C) in the warmest month of August. Winters are cold with the average low temperature around 35.2°F (1.8°C) during the coldest month of December. Spring and fall often have unpredictable weather with occasional incidents of warm and cold fronts that may push the temperatures above 80.1°F (26.7°C) or below 39.9°F (4.4°C) during the day.

The average annual sunshine in Portland is around 2341 hours with a peak around July and August. Winter has the cloudiest skies of the year as the average humidity registers above 80% most of the time during the cold season. The city experiences average annual precipitation of 36" (914.4mm) with heavy rainfall between November and February. Snowfall is light to the tune of 4.4" (111.8mm) during the winter with few incidences of frost. The temperate climate is suitable for growing roses.

The highest recorded temperature in Portland is 107.1°F (41.7°C), set on July 30, 1965, while the lowest temperature on record is -2.9°F (-19.4°C), set on February 2, 1950.
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The best time to visit Portland is during the summer from June to August when the weather is dry, the skies are clear, and the temperatures are moderate. Summer is the season of roses during which the flowers are in full bloom, and the landscape, especially the suburbs, exhibit a variety of colors. May is also a pleasant time during late spring, but the weather can be unpredictable, and showers are common during the day.

The worst time to visit Portland is during the late fall and winter months when the skies are overcast, and the weather is at the wettest of the year. November to February is a time to avoid Portland as the city faces occasional cold waves and the sunshine hardly lasts for 2 to 4 hours daily. Temperatures drop below freezing during the peak of winter with occasional snowfall. Winter visits to Portland are suitable for budget travelers who can face the chilly weather.

Portland's location in the Pacific Northwest makes it vulnerable to earthquakes. Active fault lines traverse the Portland metropolitan area, both on the east and west side, and create a possibility of magnitude 7 earthquakes. Many locations inside the city are prone to landslides and soil liquefaction during major earthquakes. Portland sits on Boring Lava Field, an extinct volcanic field and lies just 50 miles away from Mount St. Helens, an active volcano, within reach of volcanic ash.

January is wet in Portland as the New Year month sees about 4.9" (124.5mm) of heavy rainfall with mostly overcast skies. Weather in January »

February sees mild temperatures in Portland in the average range of 36°F (2.2°C) to 51.1°F (10.6°C) with an increase in the sunshine to 4 hours a day. Weather in February »

March is the beginning of the spring season in Portland, which pushes the average temperatures in the range of a mild 39.9°F (4.4°C) to a warm 57°F (13.9°C). Weather in March »

April is mid-spring in Portland as the cloudy and wet weather begins to taper off. The 2.7" (68.6mm) of rainfall is moderate and spreads over 15 days during the month. Weather in April »

The average temperatures in May in Portland are between 48.9°F (9.4°C) to 68°F (20°C) as the skies are clear for long periods. Weather in May »

The average temperatures in June are in the warm range of 54°F (12.2°C) to 73°F (22.8°C) as the long days have a humidity of 65%. Weather in June »

July is the sunniest and driest month of the year in Portland with a massive 332 hours of sunshine and only 0.6" (15.2mm) of rainfall. Weather in July »

August is the warmest month of the year in Portland, Oregon when the average temperatures peak at 81.1°F (27.3°C). Weather in August »

The average temperatures are in the warm zone of 53.1°F (11.7°C) to 75.9°F (24.4°C) with light rainfall to the tune of 1.5" (38.1mm). Weather in September »

The average temperatures in October drop to the range of 46°F (7.8°C) to 64°F (17.8°C) with a few chilly nights during the month. Weather in October »

November is the wettest month of the year in Portland with a massive 5.6" (142.2mm) of rainfall, and mostly dark skies with daily sunshine of 3 hours. Weather in November »

December is the coldest month of the year in Portland with the average temperatures in the range of a cold 35.1°F (1.7°C) to a mild 45°F (7.2°C). Weather in December »

Months with the highest number of snowfall days are February and December (1.5 days).
Months with the lowest number of snowfall days are April, May, June, July, August, September and October (0 days).