Climate and monthly weather forecastPortland, OR
Climate and monthly weather forecast
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 »Updated: Jun 4, 2024
Published by: Weather Atlas | About Us
Data Sources | Weather Forecasting & Climate
Published by: Weather Atlas | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
The months with the highest humidity are January, February and December, with an average relative humidity of 83%.
Throughout the year, there are 173.1 rainfall days, and 31.18" (792mm) of precipitation is accumulated.
January through March, November and December are months with snowfall.
Throughout the year, there are 6.4 snowfall days, and 3.94" (100mm) of snow is accumulated.
With an average of 4.1h of sunshine, January has the least sunshine of the year.
January, February, November and December, with an average maximum UV index of 2, are months with the lowest UV index.
March is the month with the most snowfall. Snow falls for 1.6 days and accumulates 1.5" (38mm) of snow.
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.
In Portland, snow does not fall in April through October.
June has the longest days of the year, with an average of 15h and 36min of daylight.
July is the month with the least rainfall. Rain falls for 4.9 days and accumulates 0.31" (8mm) of precipitation.
The month with the highest UV index in Portland is July, with an average maximum UV index of 6.
August, characterized by an average high temperature of 81.5°F (27.5°C) and a low temperature of 55°F (12.8°C), is generally the warmest month.
The least humid month in Portland is August, with an average relative humidity of 63%.
The month with the most sunshine is August, with an average of 10.9h of sunshine.
December, with its high-temperature average of 44.1°F (6.7°C) and a low-temperature average of 34.7°F (1.5°C), is the coldest month.
December is the month with the most rainfall. Rain falls for 18.5 days and accumulates 4.53" (115mm) of precipitation.
December has the shortest days of the year, with an average of 8h and 48min of daylight.
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).
Average pressure
Portland, OR
- Average pressure in January:
30.12"Hg - Average pressure in February:
30.08"Hg - Average pressure in March:
30.03"Hg - Average pressure in April:
30.06"Hg - Average pressure in May:
30.03"Hg - Average pressure in June:
30.03"Hg
- Average pressure in July:
30.03"Hg - Average pressure in August:
30"Hg - Average pressure in September:
30.01"Hg - Average pressure in October:
30.05"Hg - Average pressure in November:
30.06"Hg - Average pressure in December:
30.1"Hg
The month with the highest atmospheric pressure is January (30.12"Hg).
The month with the lowest atmospheric pressure is August (30"Hg).
Average wind speed
Portland, OR
- Average wind speed in January:
5.8mph - Average wind speed in February:
5.6mph - Average wind speed in March:
5.3mph - Average wind speed in April:
4.8mph - Average wind speed in May:
4.2mph - Average wind speed in June:
4.1mph
- Average wind speed in July:
4.1mph - Average wind speed in August:
3.9mph - Average wind speed in September:
4mph - Average wind speed in October:
4.7mph - Average wind speed in November:
5.5mph - Average wind speed in December:
5.5mph
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).
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%).
Average rainfall
Portland, OR
- Average rainfall in January:
4.33" - Average rainfall in February:
3.27" - Average rainfall in March:
3.39" - Average rainfall in April:
3.11" - Average rainfall in May:
1.77" - Average rainfall in June:
1.46"
- Average rainfall in July:
0.31" - Average rainfall in August:
0.39" - Average rainfall in September:
1.69" - Average rainfall in October:
3.39" - Average rainfall in November:
3.54" - Average rainfall in December:
4.53"
The wettest month (with the highest rainfall) is December (4.53").
The driest month (with the least rainfall) is July (0.31").
Average rainfall days
Portland, OR
- Average rainfall days in January:
18.3 days - Average rainfall days in February:
16.9 days - Average rainfall days in March:
20.4 days - Average rainfall days in April:
18.8 days - Average rainfall days in May:
13.8 days - Average rainfall days in June:
11.3 days
- Average rainfall days in July:
4.9 days - Average rainfall days in August:
5.2 days - Average rainfall days in September:
10.4 days - Average rainfall days in October:
15.8 days - Average rainfall days in November:
18.8 days - Average rainfall days in December:
18.5 days
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).
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").
Average snowfall days
Portland, OR
- Average snowfall days in January:
1.3 days - Average snowfall days in February:
2.3 days - Average snowfall days in March:
1.6 days - Average snowfall days in April:
0.1 days - Average snowfall days in May:
0 days - Average snowfall days in June:
0 days
- Average snowfall days in July:
0 days - Average snowfall days in August:
0 days - Average snowfall days in September:
0 days - Average snowfall days in October:
0 days - Average snowfall days in November:
0.3 days - Average snowfall days in December:
0.8 days
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).
Average daylight / Average sunshine
Portland, OR
- Average daylight in January:
9h and 12min - Average daylight in February:
10h and 24min - Average daylight in March:
12h and 0min - Average daylight in April:
13h and 36min - Average daylight in May:
14h and 54min - Average daylight in June:
15h and 36min
- Average daylight in July:
15h and 18min - Average daylight in August:
14h and 6min - Average daylight in September:
12h and 30min - Average daylight in October:
10h and 54min - Average daylight in November:
9h and 30min - Average daylight in December:
8h and 48min
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).
- Average sunshine in January:
4h and 6min - Average sunshine in February:
4h and 12min - Average sunshine in March:
5h and 54min - Average sunshine in April:
7h and 42min - Average sunshine in May:
8h and 42min - Average sunshine in June:
9h and 18min
- Average sunshine in July:
10h and 48min - Average sunshine in August:
10h and 54min - Average sunshine in September:
9h and 18min - Average sunshine in October:
5h and 30min - Average sunshine in November:
4h and 36min - Average sunshine in December:
4h and 18min
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).
Average sunshine days
Portland, OR
- Average sunshine days in January:
10.8 days - Average sunshine days in February:
8.5 days - Average sunshine days in March:
8.3 days - Average sunshine days in April:
8.8 days - Average sunshine days in May:
14.8 days - Average sunshine days in June:
16 days
- Average sunshine days in July:
23.8 days - Average sunshine days in August:
23.8 days - Average sunshine days in September:
17.4 days - Average sunshine days in October:
13.9 days - Average sunshine days in November:
9.9 days - Average sunshine days in December:
10.5 days
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).
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).
Average cloud cover
Portland, OR
The month with the most cloud cover is February (Cloud cover 58).
The month with the least cloud cover is August (Cloud cover 23).
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).
