Climate and monthly weather forecast
Portland, OR

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A colorful autumn view of the outline of Portland City, Oregon, USA
A colorful autumn view of the outline of Portland City, Oregon, USA

The climate of Portland

Portland, situated in the state of Oregon, USA, is blessed with a Mediterranean, warm summer climate, also referred to as Csb in the Köppen climate classification. This type of climate is characterized by dry, warm summers and mild, wet winters, with precipitation often concentrated in the colder part of the year.

Throughout the year, one can observe a varying trend in the climate of Portland. Temperatures oscillate from a low of 34.7°F (1.5°C) in winter to a summertime high of about 81.5°F (27.5°C). Between January and December, the city undergoes a substantial temperature increase from 35.2°F (1.8°C) to 81.5°F (27.5°C) with the summer months witnessing the pick of the heat.

The highest rainfall is recorded from December to February, with December experiencing the maximum annual precipitation of 4.53" (115mm). However, during the summer months of July and August, the city experiences minimum rainfall, which is in sharp contrast with the winters. On average, snowfall in Portland over the year is relatively low and mainly focused in the winter months, with a slight possibility in November and December.

The best time to visit Portland

Summer, from June to August, is arguably the best time to visit Portland. The city bursts into life as temperatures reach a comfortable average high of 80.6°F (27°C) in July and a high of 81.5°F (27.5°C) in August. With approximately 9.3 to 10.8 hours of sunshine per day and a substantially low 0.31" (8mm) of rainfall in July, it is indeed a brilliant time to explore the city. Besides, the UV index of 6 makes it safer for visitors to enjoy outdoor activities.

The worst time to visit Portland

Winter months from December to February are considered the least favorable time to visit Portland. Temperatures drop to a low of 34.7°F (1.5°C) in December, making the weather rather chilly. Furthermore, the city receives the highest average rainfall of 4.53" (115mm) in December. The shorter daylight hours, averaging 8.8 to 9.5 hours, as well as a reduced visibility of 5 miles, can act as deterrents to outdoor activities and sightseeing.

Spring weather in Portland

Spring in Portland, from March to May, brings pleasant changes in weather. Temperatures pick up from the winter lows and range from an average low of 38.1°F (3.4°C) in March to a high of 67.1°F (19.5°C) in May. Relative humidity reduces from—March's 81% to May's 72%, making it agreeable for outdoor activities. Rainfall also decreases from 3.39" (86mm) in March to 1.77" (45mm) in May, marking the onset of the dry season.

Summer weather in Portland

Summers in Portland, stretching from June through August, can be described as comfortably warm with an average temperature rising from 72.1°F (22.3°C) in June to about 81.5°F (27.5°C) in August. The city basks in approximately 15.3 to 15.6 hours of daylight with sunshine hours reaching up to 10.8 to 10.9 hours per day. Furthermore, a low average rain of 0.31" (8mm) in July presents the perfect atmosphere for summer travelers.

Autumn weather in Portland

Autumn in Portland, observed from September to November, features a combination of mild weather and increasing rainfall. The temperatures slowly decline from 74.1°F (23.4°C) in September to a fall average low of about 40.3°F (4.6°C) in November. Rainfall starts to pick up from September’s 1.69" (43mm) to November’s 3.54" (90mm). Sunshine hours also gradually decrease, giving way to longer, cooler nights.

Winter weather in Portland

Winter in Portland, from December until February, is characterized by cold and wet conditions combined with shorter daylight hours. As the temperature drops from 44.1°F (6.7°C) in December to average lows of 34.7°F (1.5°C) in January, the city experiences heightened rainfall with December recording the year's wettest month at 4.53" (115mm). Snowfall, though infrequent, can occur during these months with December seeing the most at 0.28" (7mm).

Weather in January

Noted as the start of winter in Portland, Oregon, January exhibits weather patterns typical of this chilly season. According to the data, the highest amount of snowfall occurs between December and February with January witnessing a snowfall of 0.91" (23mm). Weather in January »

Weather in February

By the time February sets in, Portland starts experiencing a slight increase in average daily temperatures. Notably, this period continues to experience snowfall, albeit at a marginally reduced rate of about 1.22" (31mm) compared to January. Weather in February »

Weather in March

As March arrives, it brings along a wave of warmer weather to Portland. The month records a relatively higher rainfall of about 3.39" (86mm) which signals the dawn of spring. Light showers and mild temperatures make the landscapes of the city truly beautiful. Weather in March »

Weather in April

April in Portland is synonymous with the full bloom of Spring. There is a noticeable increase in sunshine hours, making days longer and warmer. A reduced rainfall amount of about 3.11" (79mm) marks the transition from the wet spring toward the dryer summer. Weather in April »

Weather in May

May brings in an elevated level of heat as Portland is preparing for the summer month. Significantly, this month experiences the lowest spring rainfall at around 1.77" (45mm), resulting in mostly clear and mild weather. Residents start feeling the sun's warmth enveloping the city while the natural world thrives after the rainy seasons. Weather in May »

Weather in June

June in Portland signifies the onset of summer, characterized by longer days and shorter nights. Correspondingly, the number of sunshine days increases to 16. This period witnesses the dry climate of summer with significantly reduced rainfall. Weather in June »

Weather in July

July is considered the heart of summer for Portland. The average high temperature is 80.6°F (27°C), making this the hottest month of the year. Generally, it is a dry month, providing locals and tourists with ideal conditions to enjoy the exquisite outdoors. Weather in July »

Weather in August

In August, Portland's weather remains warm and dry with the least cloud cover. As summer reaches its zenith, the city experiences the second-highest temperature of the season. However, August is also a month to enjoy a palette of vibrant sunset hues. Weather in August »

Weather in September

Localized weather patterns carry Portland from the hot, dry months of summer into the cool, wet months of fall in September. Registering 1.69" (43mm) of rainfall, the city sees a gradual increase in precipitation. Days start getting shorter, although they still remain long enough for outdoor activities. Weather in September »

Weather in October

October in Portland means the full arrival of the fall season. Rainfall starts increasing and takes a significant leap from September to reach 3.39" (86mm). However, the temperature remains pleasantly cool, and the presence of the Sun can still be felt. Weather in October »

Weather in November

November marks the shift from fall to early winter in Portland, Oregon. The city records one of the highest rainfall figures of the year at 3.54" (90mm). Winds start picking up the pace, making the atmosphere colder. Despite the descending temperatures, the city holds its charm with the remnant fall leaves and the onset of holiday season decorations. Weather in November »

Weather in December

December welcomes the winter season in full swing in Portland. The colder month brings 4.53" (115mm) of rainfall, the highest monthly average for the year. Accompanied by cooler winds, the temperatures add to the winter chill. Despite shorter days, the city brims with holiday cheer. Weather in December »
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Frequently asked questions

What is the most humid month in Portland?

January, February and December, with an average relative humidity of 83%, are most humid months.

How much does it rain in Portland?

In Portland, during the entire year, the rain falls for 173.1 days and collects up to 31.18" (792mm) of precipitation.

When does it snow in Portland?

January through March, November and December are months with snowfall in Portland.

How many days does it snow in Portland?

Throughout the year, in Portland, there are 6.4 snowfall days, and 3.94" (100mm) of snow is accumulated.

What is the month with the least sunshine in Portland?

The month with the least sunshine in Portland, Oregon, is January, with an average of 4.1h of sunshine.

What are the months with the lowest UV index in Portland?

The months with the lowest UV index are January, February, November and December, with an average maximum UV index of 2.

What is the snowiest month in Portland?

March is the month with the most snowfall. Snow falls for 1.6 days and accumulates 1.5" (38mm) of snow.

When is Daylight Saving Time (DST) in Portland?

On Sunday, March 10. 2024, at 2:00 am, Daylight Saving Time starts, and the time zone changes from PST to PDT. Daylight Saving Time ends Sunday, November 3. 2024, at 2:00 am, and the time zone reverts from PDT to PST.

When it does not snow in Portland?

April through October are months without snowfall.

When are the longest days in Portland?

With an average of 15h and 36min of daylight, June has the longest days of the year in Portland.

What is the driest month in Portland?

July is the month with the least rainfall in Portland. Rain falls for 4.9 days and accumulates 0.31" (8mm) of precipitation.

When is the highest UV index in Portland?

July is the month with the highest UV index in Portland, with an average maximum UV index of 6.

What are the warmest months in Portland?

The warmest time of the year in Portland is August, with temperatures averaging a high of 81.5°F (27.5°C) and a low of 55°F (12.8°C).

What is the least humid month in Portland?

With an average relative humidity of 63%, August is the least humid month in Portland, Oregon.

What month has the most sunshine in Portland?

The month with the most sunshine is August, with an average of 10.9h of sunshine.

What month is the coldest in Portland?

During the coldest month in Portland, December, temperatures average a high of 44.1°F (6.7°C) and a low of 34.7°F (1.5°C).

What is the wettest month in Portland?

The month with the most rainfall in Portland is December, when the rain falls for 18.5 days and typically aggregates up to 4.53" (115mm) of precipitation.

What is the month with the shortest days in Portland?

December has the shortest days of the year in Portland, Oregon, with an average of 8h and 48min of daylight.

Average temperature
Portland, OR

Average temperature - Portland, OR

The warmest month (with the highest average high temperature) is August (81.5°F).
The month with the lowest average high temperature is December (44.1°F).

The month with the highest average low temperature is August (55°F).
The coldest month (with the lowest average low temperature) is December (34.7°F).

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Average pressure
Portland, OR

Average pressure - Portland, OR

The month with the highest atmospheric pressure is January (30.12"Hg).
The month with the lowest atmospheric pressure is August (30"Hg).

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Average wind speed
Portland, OR

Average wind speed - Portland, OR

The windiest month (with the highest average wind speed) is January (5.8mph).
The calmest month (with the lowest average wind speed) is August (3.9mph).

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Average humidity
Portland, OR

Average humidity - Portland, OR

The months with the highest relative humidity are January, February and December (83%).
The month with the lowest relative humidity is August (63%).

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Average rainfall
Portland, OR

Average rainfall - Portland, OR

The wettest month (with the highest rainfall) is December (4.53").
The driest month (with the least rainfall) is July (0.31").

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Average rainfall days
Portland, OR

Average rainfall days - Portland, OR

The month with the highest number of rainy days is March (20.4 days).
The month with the least rainy days is July (4.9 days).

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Average snowfall
Portland, OR

Average snowfall - Portland, OR

The month with the highest snowfall is March (1.5").
The months with the least snowfall are April, May, June, July, August, September and October (0").

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Average snowfall days
Portland, OR

Average snowfall days - Portland, OR

The month with the highest number of snowfall days is February (2.3 days).
The months with the least snowfall days are May, June, July, August, September and October (0 days).

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Average daylight / Average sunshine
Portland, OR

Average daylight / Average sunshine - Portland, OR

The month with the longest days is June (Average daylight: 15h and 36min).
The month with the shortest days is December (Average daylight: 8h and 48min).

The month with the most sunshine is August (Average sunshine: 10h and 54min).
The month with the least sunshine is January (Average sunshine: 4h and 6min).

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Average sunshine days
Portland, OR

Average sunshine days - Portland, OR

The months with the most sunshine days are July and August (23.8 days).
The month with the least sunshine days is March (8.3 days).

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Average UV index
Portland, OR

Average UV index - Portland, OR

The month with the highest UV index is July (UV index 6).
The months with the lowest UV index are January, February, November and December (UV index 2).

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Average visibility
Portland, OR

Average visibility - Portland, OR

The months with the highest visibility are July, August and September (6mi).
The months with the lowest visibility are January, February, March, April, May, June, October, November and December (5mi).

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Portland, Oregon, USA

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