Last updated: February 24, 2025
May in Portland, United States, brings a delightful mix of weather as spring transitions into summer. With maximum temperatures reaching 24°C (76°F) and average daily temperatures around 11°C (52°F), the month offers pleasant days for outdoor activities. However, mornings can be crisp, with minimum temperatures dropping to 2°C (36°F). Rain is common, with total precipitation accumulating to 94 mm (3.7 in) over about 10 days, contributing to the city's lush greenery. The humidity, averaging 72%, adds a refreshing, vibrant feel to the air, defining the charm of Portland in May.
In May, Portland's temperatures begin to warm up, offering a refreshing transition from the lingering chill of winter. With minimums around 2°C (36°F) and an average of 11°C (52°F), spring starts to take hold, inviting residents to enjoy the outdoors. The highs can soar to 24°C (76°F), presenting perfect conditions for everything from picnics in the park to leisurely strolls along the waterfront. As the month progresses, the city sheds its cooler layers, signaling the approach of summer warmth and the vibrant energy that accompanies longer days. This trend reflects an upward trajectory in temperatures as we move through spring, culminating in a delightful experience for both locals and visitors alike.
In May, Portland experiences a moderate shift in precipitation, recording 94 mm (3.7 in) over 10 days. This amount reflects a slight dip from the preceding month of April, which saw 149 mm (5.9 in), making May a comparatively drier time as the city transitions toward summer. While the rainfall is less intense than April's peak, it maintains the characteristic spring freshness, contributing to the lush greenery that defines the region. As the weather warms, the 10 precipitation days in May coincide with an overall trend of decreasing rainfall leading into the dry months of June and July, where average totals continue to decline. This pattern emphasizes Portland's reputation for having both wet and dry seasons, allowing residents to enjoy the blossoms of spring while anticipating sunnier days ahead.
In May, Portland experiences a notable shift in humidity, with levels dropping to 72% from the higher averages of the earlier months. This gradual decrease signals the arrival of warmer weather, as the city transitions from the damp chill of winter and early spring. Interestingly, the humidity remains consistent throughout June, suggesting a stable climate as the summer approaches. Compared to the peak levels of 86% in January, May's conditions offer a refreshing change, making it an ideal time for outdoor activities as the city shakes off the winter moisture. As the summer months unfold, humidity continues its decline, reaching the lowest points in July and August, hinting at a balance between warm temperatures and comfortable air.
As May arrives in Portland, the UV Index soars to 9, categorizing exposure as very high and reducing burn time to just 15 minutes. This significant increase from the earlier months highlights a notable trend in the season's progression from the low UV levels of winter to the intense rays of late spring. Following a steady climb from January's UV Index of 2, the month of April already marked a shift to a high exposure category with an Index of 7. With May's UV Index peaking before summer, it serves as a reminder for residents and visitors to take sun safety precautions seriously. Whether you're soaking in the sun at a local park or enjoying outdoor activities, protecting your skin is crucial. For more insights, check out the detailed UV data here: Portland UV Index.
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As spring transitions into summer, May in Portland shines brightly with an impressive 294 hours of sunshine. This month marks a noticeable uplift from the previous months, showcasing a delightful increase from 244 hours in April. The trend continues upward as Portlanders relish longer, sunnier days, setting the stage for the peak sunlight of June and July. With each passing month from January's meager 148 hours to the blossoming warmth of May, residents eagerly embrace the vibrant, sun-kissed days that herald the arrival of summer, making outdoor adventures ever more enticing.
In May, the likelihood of sunny weather in Portland is somewhat modest, with a 37% chance of sunshine. This follows a pattern seen in the spring months, where the sun shines more brightly in March at 61% but dwindles as we transition into April with a 36% probability. Interestingly, as we move into the summer months, the chances of sunny days begin to rise again, peaking in June at 40%. Overall, May's sunshine forecast reflects the city’s characteristic variability, hinting at a blend of cloudy and clear days as the region nears its sunnier season, while maintaining the trend of occasional brightness amidst the spring showers.
As the year progresses in Portland, the daylight duration reveals a captivating transformation, particularly noticeable in May when the city enjoys approximately 14 hours of sunlight. This marks a significant increase from the 11 hours of daylight in March and a remarkable leap from the 10 hours in February. Following a steady rise through April, May serves as a bridge to the longest days of summer in June and July, both boasting 15 hours of light. This gradual lengthening of days invites residents outdoors, encouraging vibrant spring activities and connection with nature before the summer season begins to ebb. As autumn approaches, the trend reverses, transitioning back to shorter days, emphasizing the fleeting beauty of Portland’s seasonal daylight.
In May, Portland experiences a slight dip in wind speed, averaging 4.0 m/s (9 mph), making it one of the calmer months compared to the gustier spring months. Notably, this breeze paves the way for idyllic outdoor activities as the city transitions into the warmer season. The wind speeds trend downward throughout the summer, with July and August bringing milder conditions at 3.4 m/s (8 mph) and 3.3 m/s (7 mph), respectively. However, as autumn approaches, wind speeds begin to climb again, with September and October returning to a refreshing 4.0 m/s (9 mph) and 4.2 m/s (9 mph). This pattern highlights Portland's characteristic variability, where spring's breezy charm gives way to the lazy winds of summer before reviving enthusiasm in the fall.
The weather in Portland changes throughout the year, offering a unique experience in each season. Below is a month-by-month comparison of May'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.
May and January present stark contrasts in weather. In May, temperatures range from a chilly 2°C (36°F) to a warm 24°C (76°F), with an average of 11°C (52°F), while January experiences much colder conditions, with a minimum of -19°C (-2°F) and a maximum of 12°C (54°F), averaging -2°C (28°F). Both months see similar precipitation levels, with May receiving 94 mm (3.7 in) over about 10 days and January slightly higher at 97 mm (3.8 in) over 9 days. Additionally, humidity is higher in January at 86%, compared to May's 72%, contributing to the wintry feel of the first month of the year. For more details on January weather in Portland, you can check Portland weather in January.
May and February present stark contrasts in weather conditions. In May, temperatures range from a cool 2°C (36°F) overnight to a pleasant high of 24°C (76°F) during the day, with an average of 11°C (52°F). The month sees about 94 mm (3.7 in) of precipitation spread over 10 days, accompanied by a humidity level of 72%. In contrast, February is characterized by much colder temperatures, starting at a frigid minimum of -17°C (2°F) and only reaching a maximum of 14°C (57°F), with an average of -2°C (29°F). Despite February's slightly higher precipitation of 103 mm (4.1 in) across the same number of days, the humidity is notably higher at 84%. For a more detailed view, check out the Portland weather in February.
In comparing the weather between March and May, it's clear that May offers a mild and pleasant climate, with average temperatures rising to 11°C (52°F) and maximums reaching up to 24°C (76°F). In contrast, March experiences much colder conditions, marked by an average temperature of just 1°C (34°F) and a minimum that can plummet to -15°C (6°F). Both months see similar levels of precipitation, with May receiving slightly more at 94 mm (3.7 in) compared to March's 91 mm (3.6 in), but March has a slightly lower number of rainy days (9). Additionally, humidity levels are higher in March at 82% versus 72% in May, contributing to the chillier atmosphere. For a more detailed look at March weather, you can check Portland weather in March.
In comparing the weather of April and May, we see a notable shift in temperatures and precipitation. May enjoys milder conditions with temperatures ranging from a minimum of 2°C (36°F) to a maximum of 24°C (76°F), averaging 11°C (52°F). In contrast, April is cooler with temperatures ranging from a minimum of -3°C (27°F) to a maximum of 18°C (65°F), averaging only 6°C (43°F). While May has a lower total precipitation of 94 mm (3.7 inches) over 10 rainy days, April experiences higher rainfall at 149 mm (5.9 inches) across 13 days, contributing to a slightly more humid atmosphere with an average humidity of 80%. For a deeper look at April's climate, you can visit Portland weather in April.
May and June exhibit a noticeable transition in weather patterns. In May, temperatures range from a minimum of 2°C (36°F) to a maximum of 24°C (76°F), with an average of 11°C (52°F), while June sees a warmer minimum of 8°C (47°F) and a maximum of 28°C (83°F), averaging 17°C (62°F). Precipitation decreases slightly from 94 mm (3.7 in) over 10 days in May to 80 mm (3.2 in) across 9 days in June, with humidity remaining constant at 72% throughout both months. This shift heralds the arrival of summer, as June often brings sunnier days compared to the cooler, wetter May. For more detailed information, you can check Portland weather in June.
May and July present distinct weather patterns, showcasing the transition from spring to summer. In May, temperatures range from a cool minimum of 2°C (36°F) to a pleasant maximum of 24°C (76°F), with an average temperature of 11°C (52°F). The month experiences about 94 mm (3.7 inches) of precipitation over 10 days, and humidity levels are relatively high at 72%. In contrast, July offers a warmer climate, with minimum temperatures starting at 13°C (56°F) and peaking at 28°C (83°F), resulting in a comfortable average of 20°C (68°F). While July sees increased precipitation of 123 mm (4.9 inches) across 12 days, humidity drops slightly to 67%. For a more detailed look at July weather in Portland, visit Portland weather in July.
May and August exhibit distinctly different weather patterns. In May, temperatures range from a cool 2°C (36°F) at night to a pleasant maximum of 24°C (76°F) during the day, with an average of 11°C (52°F). The month receives about 94 mm (3.7 in) of precipitation over roughly 10 days, accompanied by a humidity level of 72%. In contrast, August experiences milder conditions, with temperatures starting at a minimum of 14°C (57°F) and peaking at 28°C (82°F), averaging around 20°C (69°F). Precipitation decreases to 75 mm (3.0 in) across 9 days, and humidity drops slightly to 66%. For more details, you can check Portland weather in August.
May and September exhibit distinct weather patterns that reflect the transition between spring and autumn. In May, temperatures range from a crisp 2°C (36°F) to a pleasant 24°C (76°F), with an average temperature of 11°C (52°F). The month sees a higher amount of precipitation, totaling 94 mm (3.7 inches) over approximately 10 days, accompanied by humidity levels around 72%. In contrast, September offers slightly warmer temperatures, with a minimum of 8°C (46°F) and a maximum of 26°C (79°F), averaging 17°C (63°F). Precipitation decreases to 77 mm (3.0 inches) over 8 days, while humidity remains relatively stable at 71%. Overall, September tends to be drier and warmer than May, making it a pleasant time for outdoor activities. For more details on September weather, check out Portland weather in September.
May and October showcase a transition in weather patterns, with both months offering distinct characteristics. In May, temperatures typically range from a minimum of 2°C (36°F) to a maximum of 24°C (76°F), resulting in an average temperature of 11°C (52°F). This month experiences about 94 mm (3.7 in) of precipitation over 10 days, with a humidity level of 72%. Conversely, October sees slightly cooler temperatures, with a minimum of 1°C (34°F) and a maximum of 21°C (71°F), averaging 12°C (54°F). The month is marked by increased rainfall, totaling 163 mm (6.4 in) across 13 days, and higher humidity at 78%. For a detailed look at October weather specifics, you can visit Portland weather in October.
May and November present contrasting weather conditions. In May, temperatures range from a minimum of 2°C (36°F) to a pleasant maximum of 24°C (76°F), with an average of 11°C (52°F). The month sees about 94 mm (3.7 in) of precipitation over roughly 10 days, accompanied by a humidity level of 72%. In stark contrast, November experiences much colder temperatures, with a minimum of -12°C (11°F) and a maximum of only 18°C (64°F), averaging at 5°C (42°F). This month is wetter, with 130 mm (5.1 in) of precipitation spread across 12 days and a higher humidity of 84%. For a more detailed look at November's weather specifics, check out Portland weather in November.
May and December present stark contrasts in weather conditions. In May, temperatures range from a mild 2°C (36°F) at night to a pleasant 24°C (76°F) during the day, with an average temperature of 11°C (52°F). The month experiences approximately 94 mm (3.7 in) of precipitation over about 10 days, accompanied by a humidity level of 72%. In contrast, December brings a much colder climate, with temperatures dipping as low as -18°C (-1°F) and peaking at 13°C (57°F), averaging around 0°C (33°F). Precipitation increases to 144 mm (5.7 in) across the same number of rainy days, and humidity rises to 81%. For more information on December weather, visit Portland weather in December.
As May unfolds in Portland, it heralds a distinct transition from the earlier chill of spring to more vibrant and temperate days. This month stands out with its mild average temperatures, making it ideal for outdoor activities and exploring the blooming landscapes. While precipitation is still present, with about ten rainy days, it is a welcome change from the heavier rains of April. The humidity level remains relatively moderate, contributing to the refreshing feel in the air. Overall, May strikes a harmonious balance, inviting residents and visitors alike to relish the outdoors before the summer heat sets in. To learn more about the weather patterns and variables affecting this dynamic city, check out Portland Climate.