Last updated: February 24, 2025
In December, Portland experiences a dynamic climate characterized by cool temperatures and significant precipitation. The month sees a maximum of 13°C (57°F) and dips to a chilly -18°C (-1°F), averaging around 0°C (33°F). With about 144 mm (5.7 in) of rain spread over 10 days, residents can expect a damp atmosphere complemented by high humidity levels averaging 81%. This interplay of cool air and moisture creates a quintessentially wintry ambiance, perfect for enjoying local seasonal festivities.
In Portland, United States, December ushers in the chill of winter, with temperatures typically ranging from a brisk -18°C (0°F) at night to a milder 13°C (57°F) during the day. This month marks a noticeable drop compared to the preceding months, as the average temperature plunges to 0°C (33°F), illustrating the season's embrace. A striking contrast to November, where milder late-fall temps still hinted at warmth, December firmly establishes Portland in its winter cold, making for cozy indoor atmospheres and the potential for snowy scenes. As the year draws to a close, residents and visitors alike feel the festive chill, perfect for warm drinks and outdoor winter activities while bundling up against the frosty air.
In December, **Portland experiences a noteworthy uptick in precipitation, with an average of 144 mm (5.7 in) over approximately 10 days of rain. This marks a significant increase from the drier summer months, highlighting the city's transition into its wetter winter season. Comparatively, December's rainfall is lower than the 163 mm (6.4 in) recorded in October but precedes November's total of 130 mm (5.1 in). As temperatures drop and daylight decreases, this trend of increased precipitation continues, emphasizing the region's characteristic reliance on winter rains to replenish its lush landscapes. The consistent pattern of rain throughout the month also underscores Portland's identity as a city that thrives in its picturesque, if sometimes soggy, environment.
In December, Portland experiences a humidity level of 81%, marking a slight decrease from the wetter months of November and January which hover in the mid-80s. This seasonal dip aligns with a gradual trend observed throughout the year, where humidity tends to peak in the colder months and gradually decline during the summer. Notably, June and July represent the city's most comfortable humidity levels, dropping to 67% and 66% respectively. However, as the year winds down, the air in December remains relatively moist, a characteristic feature of Portland's winter climate, setting a juxtaposition against the drier summer months. This cyclical pattern of humidity reinforces the city's reputation for a lush, often rainy atmosphere during the colder season, balancing between comfort and dampness.
December in Portland sees a UV Index of 2, categorizing it as low exposure. This trend mirrors the beginning of the year, highlighting a consistent pattern of minimal UV radiation during the winter months. With a burn time of 45 minutes, residents can enjoy outdoor activities with relatively less concern for sun damage. This month’s conditions are a refreshing shift from the high and very high indexes prevalent from late spring through summer, where burn times dropped to as little as 15 minutes. As you plan your winter outings, remember to stay informed about the UV levels throughout the year by visiting Portland UV Index.
UV Risk Categories
In Portland, December brings 174 hours of sunlight, marking a subtle decline compared to the vibrant months of summer, which peak at 336 hours in August. As the year winds down, daylight diminishes gradually from the summer highs, yet December still enjoys a commendable amount of sun — significantly more than the dreary January, which starts the year with just 148 hours. This month's sunlight hints at the winter's embrace, following the trend of increased hours through the spring and summer, highlighting the region's transition from the bright glow of late summer to the cooler, softer light of winter. Overall, the data reflects a rhythm of light that encourages Portlanders to savor the sunny moments amid the cozy seasonal changes.
As winter settles in, the likelihood of sunny weather in December in Portland tends to dwindle, with chances sitting at a modest 33%. This marks a continuation of a trend observed throughout the colder months; November gives a brief respite with a 54% chance of sunshine, yet both December and the earlier winter months show a notable decline compared to the spring months, where March peaks impressively at 61%. With the transition into the new year, sunny days increasingly become a rarity, reflecting the overarching pattern of Portland's persistent cloud cover during winter. As the year winds down, those holding out hope for sunny outings in December may want to factor in the city's typical overcast skies.
In Portland, the daylight duration undergoes a noticeable transformation throughout the year, with December marking a low point at just 8 hours of daylight. This reduction in light stands in stark contrast to the longest days of summer, where June and July reclaim an impressive 15 hours each. As the year progresses from January's 9 hours to December's decline, the trend highlights a gentle yet persistent ebb and flow of sunlight. The gradual increase in daylight from the winter solstice, alongside the eventual return to longer days in spring, reflects the rhythmic cycle of the seasons, inviting a sense of renewal and hope as the days begin to lengthen again.
As December rolls into Portland, the city's winds whisper a familiar tune, with average speeds returning to 4.8 m/s (11 mph). This slight uptick mirrors January's breezy onset, suggesting a seasonal consistency in the gusts that sweep through the streets. Throughout the year, wind speeds fluctuate gently, peaking in March at 5.3 m/s (12 mph) before tapering down to a calm 3.3 m/s (7 mph) in August. However, as the year draws to a close, the winds regain their strength, hinting at the energetic pulse of the Pacific Northwest that invigorates both nature and those who brave the elements. This rhythmic pattern invites Portlanders to relish in the bracing air, reminding them that even in cooler months, the winds carry a lively spirit.
The weather in Portland changes throughout the year, offering a unique experience in each season. Below is a month-by-month comparison of December's weather with other months, highlighting differences in temperature, precipitation, and other key factors. Click on each section to discover seasonal trends in Portland and find detailed weather information for every month.
In December, the weather is characterized by a moderate average temperature of 0°C (33°F) and sees a maximum of 13°C (57°F), while experiencing significant precipitation of 144 mm (5.7 in) over about 10 days. The humidity during this month is relatively high at 81%. In contrast, January tends to be slightly colder, with a minimum temperature of -19°C (-2°F) and an average of -2°C (28°F), though it still reaches a maximum of 12°C (54°F). Precipitation decreases to 97 mm (3.8 in) over 9 days, and humidity increases slightly to 86%. For more detailed weather information, check out Portland weather in January.
December and February present quite similar weather patterns, although February tends to be slightly colder. In December, temperatures range from a minimum of -18°C (1°F) to a maximum of 13°C (57°F) with an average of 0°C (33°F). It features a higher precipitation level of 144 mm (5.7 in) over about 10 days, and humidity sits around 81%. In contrast, February's temperatures range from a minimum of -17°C (2°F) to a maximum of 14°C (57°F), with an average temperature of -2°C (29°F). This month experiences less precipitation at 103 mm (4.1 in), while the humidity slightly increases to 84%. For more details on February weather trends, you can check Portland weather in February.
December and March both have relatively cold temperatures, with December experiencing slightly cooler averages. In December, the temperatures range from a minimum of -18°C (0°F) to a maximum of 13°C (57°F), while March shows a similar max temperature but with a higher average of 1°C (34°F). Precipitation is more frequent in December, totaling 144 mm (5.7 in) over 10 days, compared to March's 91 mm (3.6 in) over 9 days. Humidity levels remain comparable, with December at 81% and March at 82%. For more detailed insights on March weather, you can refer to Portland weather in March.
Comparing the weather in December and April reveals distinct seasonal characteristics. December often presents a colder atmosphere, with temperatures ranging from a frigid -18°C (1°F) to a milder maximum of 13°C (57°F) and an average of 0°C (33°F). Precipitation is significant during this month, totaling 144 mm (5.7 in) over approximately 10 days, accompanied by high humidity levels around 81%. In contrast, April brings a noticeable warming trend, with temperatures varying from a low of -3°C (27°F) to a pleasant high of 18°C (65°F), averaging 6°C (43°F). Though April sees slightly higher precipitation at 149 mm (5.9 in) across about 13 days, humidity remains relatively stable at 80%. For more detailed insights on April’s weather trends, visit Portland weather in April.
December weather is characterized by much colder temperatures, with averages around 0°C (33°F) and occasional drops to a minimum of -18°C (-1°F). In contrast, May heralds the arrival of spring with milder conditions, featuring an average temperature of 11°C (52°F) and highs reaching up to 24°C (76°F). While both months experience about 10 days of precipitation, December sees significantly more rainfall at 144 mm (5.7 in) compared to May's 94 mm (3.7 in). Additionally, December's humidity averages around 81%, making it feel more chilling than May's lower humidity level of 72%. For more detailed insights into May's climate, you can visit Portland weather in May.
December and June present a striking contrast in weather conditions. In December, temperatures can plummet as low as -18°C (1°F) and average around 0°C (33°F), while the maximum rarely exceeds 13°C (57°F). This month also sees significant precipitation, totaling 144 mm (5.7 in), on about 10 days, accompanied by high humidity at 81%. In contrast, June offers a much milder climate, with minimum temperatures starting at 8°C (47°F) and averaging 17°C (62°F), peaking at a warm 28°C (83°F). With lower precipitation of 80 mm (3.2 in) over just 9 days and reduced humidity at 72%, June is undoubtedly a more comfortable and inviting month. For a deeper dive into the specific weather trends of June, check out Portland weather in June.
In December, the weather is characterized by cold temperatures, with a minimum of -18°C (1°F) and an average of around 0°C (33°F), making it a chilly month overall. Precipitation is relatively high at 144 mm (5.7 in), occurring over approximately 10 days, and humidity is notably high at 81%. In contrast, July brings warmth with temperatures ranging from a minimum of 13°C (56°F) to a maximum of 28°C (83°F), averaging around 20°C (68°F). With 123 mm (4.9 in) of precipitation over 12 days and lower humidity at 67%, July offers a much more pleasant and comfortable climate. For more details on July weather, you can visit Portland weather in July.
December and August present stark contrasts in weather patterns. In December, temperatures plunge to a minimum of -18°C (1°F) and average around 0°C (33°F), with a maximum reaching only 13°C (57°F). This month also sees substantial precipitation with 144 mm (5.7 in) over approximately 10 days, and high humidity at 81%. In contrast, August boasts milder temperatures, with a minimum of 14°C (57°F) and an average of 20°C (69°F), peaking at 28°C (82°F). Precipitation is notably lighter at 75 mm (3.0 in) spread over 9 days, coupled with lower humidity of 66%. For a more detailed look at August weather specifics, visit Portland weather in August.
December and September showcase a stark contrast in weather patterns. December's temperatures range from a biting minimum of -18°C (1°F) to a maximum of 13°C (57°F), with an average hovering around freezing at 0°C (33°F). In contrast, September enjoys milder conditions, with minimum temperatures at 8°C (46°F) and desirable highs reaching 26°C (79°F), resulting in a comfortable average of 17°C (63°F). While December sees higher precipitation at 144 mm (5.7 in) over approximately 10 days, September's weather is comparatively drier, with 77 mm (3.0 in) falling over just 8 days. Humidity also differs, with December presenting a moist 81% compared to 71% in September, further emphasizing the seasonal shift. For more details on Portland's September weather, visit Portland weather in September.
December weather is significantly colder compared to October, with average temperatures hovering around 0°C (33°F) as opposed to October’s milder average of 12°C (54°F). While December experiences lower temperatures, it also has noteworthy precipitation, with 144 mm (5.7 in) over about 10 days, compared to October's higher rainfall of 163 mm (6.4 in) over 13 days. Humidity remains relatively high in both months, with December at 81% and October slightly lower at 78%. For a more detailed look at what to expect during this month in Portland, check out Portland weather in October.
In comparing the weather between December and November, December showcases significantly colder temperatures, with a minimum of -18°C (1°F) and an average of 0°C (33°F), whereas November has milder conditions, starting at a minimum of -12°C (11°F) and averaging around 5°C (42°F). While December experiences slightly more precipitation with 144 mm (5.7 in) over about 10 days, November's rainfall is marginally lower at 130 mm (5.1 in) across 12 days. Humidity levels are relatively similar, with December at 81% and November at 84%. For a more detailed look at November weather patterns, you can refer to Portland weather in November.
As December settles over Portland, the weather transforms into a cooler and wetter season, standing in stark contrast to the milder months that precede it. With average temperatures hovering around 0°C (33°F), December brings the unmistakable chill of winter, occasionally dipping to -18°C (-1°F) during the night. This month also sees increased precipitation, contributing to a damp atmosphere with 144 mm (5.7 in) of rain over about 10 days. Coupled with humidity levels soaring to 81%, the air feels notably colder and heavier. For those seeking greater insights into Portland's unique climate, visit Portland Climate to explore seasonal variations.