Last updated: June 24, 2025
In Hillsboro, United States, the average temperature in December hovers around 2°C (36°F), with the potential to dip as low as -25°C (-13°F) or rise to a pleasant 18°C (64°F). Be prepared for 67 mm (2.7 in) of precipitation spread over 10 days, and brace yourself for the humidity, which averages a damp 87%.
In December in Hillsboro, the average temperature is 2°C (36°F). The maximum can reach 18°C (64°F) and the minimum can be as low as -25°C (-13°F). Travelers should be prepared for a wide range of temperatures, from chilly days to much warmer afternoons, making layered clothing essential.
In Hillsboro in December, the precipitation amount is 67 mm (2.7 in) over a span of 10 days.
In Hillsboro in December, humidity is 87%. With an average temperature of 2°C (36°F), this humidity feels like an unwelcome chill that seeps into your bones, making outdoor exploration feel damp and heavy, and encouraging travelers to seek the warmth of indoor attractions instead.
In Hillsboro in December, the maximum UV index is 3, which corresponds to a moderate Exposure Category. The time to burn is approximately 30 minutes. For more details on the hourly UV index in Hillsboro, you can check the information here.
UV Risk Categories
Weather in Hillsboro varies notably across the year, with each month offering distinct climate conditions. This page compares December’s weather to other months in Hillsboro, focusing on differences in temperature, rainfall, humidity, and UV levels.
| Temperature | Precipitation | Humidity | UV | |
|---|---|---|---|---|
| January Weather | -2°C (30°F) | 80 mm (3.2 inches) | 87% | moderate |
| February Weather | 0°C (33°F) | 81 mm (3.2 inches) | 85% | moderate |
| March Weather | 6°C (43°F) | 114 mm (4.5 inches) | 86% | high |
| April Weather | 11°C (52°F) | 104 mm (4.1 inches) | 84% | very high |
| May Weather | 18°C (65°F) | 149 mm (5.8 inches) | 79% | very high |
| June Weather | 23°C (75°F) | 103 mm (4.1 inches) | 82% | extreme |
| July Weather | 25°C (77°F) | 101 mm (4.0 inches) | 79% | very high |
| August Weather | 24°C (75°F) | 108 mm (4.2 inches) | 70% | very high |
| September Weather | 21°C (70°F) | 66 mm (2.6 inches) | 69% | very high |
| October Weather | 14°C (58°F) | 119 mm (4.7 inches) | 76% | high |
| November Weather | 5°C (42°F) | 81 mm (3.2 inches) | 88% | moderate |
| December Weather | 2°C (36°F) | 67 mm (2.7 inches) | 87% | moderate |