Last updated: June 24, 2025
In Portland, United States, the average temperature in December hovers around -3°C (27°F). However, be prepared for extremes, as temperatures can dip to a chilling -24°C (-11°F) or rise to a pleasant 18°C (64°F). During this month, expect approximately 44 mm (1.7 in) of precipitation spread over 7 days, accompanied by an average humidity of 82%.
In December in Portland, the average temperature is -3°C (27°F), with a maximum that can reach 18°C (64°F) and a minimum that can drop as low as -24°C (-11°F). Travelers should prepare for a wide range of temperatures and pack accordingly to enjoy their time in Portland.
In Portland in December, the precipitation amount is 44 mm (1.7 in) spread over a duration of 7 days.
In Portland in December, humidity is 82%. With an average temperature of -3°C (27°F), this humidity feels like a biting chill that seeps into your bones, making traveling uncomfortable and necessitating extra layers to stay warm while navigating through the damp air.
In Portland in December, the maximum UV index is 2, which corresponds to a low exposure category. With this level of UV radiation, the time to burn is approximately 45 minutes. To learn more about the hourly UV index in Portland, you can visit Hourly UV Index in Portland.
UV Risk Categories
Weather in Portland varies notably across the year, with each month offering distinct climate conditions. This page compares December’s weather to other months in Portland, focusing on differences in temperature, rainfall, humidity, and UV levels.
| Temperature | Precipitation | Humidity | UV | |
|---|---|---|---|---|
| January Weather | -7°C (20°F) | 38 mm (1.5 inches) | 84% | low |
| February Weather | -6°C (21°F) | 54 mm (2.1 inches) | 85% | moderate |
| March Weather | 2°C (35°F) | 60 mm (2.3 inches) | 84% | moderate |
| April Weather | 7°C (45°F) | 92 mm (3.6 inches) | 83% | very high |
| May Weather | 15°C (59°F) | 139 mm (5.5 inches) | 75% | very high |
| June Weather | 21°C (70°F) | 124 mm (4.9 inches) | 79% | very high |
| July Weather | 23°C (74°F) | 112 mm (4.4 inches) | 75% | very high |
| August Weather | 21°C (70°F) | 112 mm (4.4 inches) | 69% | very high |
| September Weather | 18°C (64°F) | 111 mm (4.4 inches) | 74% | very high |
| October Weather | 10°C (50°F) | 119 mm (4.7 inches) | 79% | moderate |
| November Weather | 1°C (35°F) | 53 mm (2.1 inches) | 88% | moderate |
| December Weather | -3°C (27°F) | 44 mm (1.7 inches) | 82% | low |