Last updated: June 24, 2025
In December, the average temperature in Happy Valley, United States hovers around -1°C (31°F), with minimums dipping to -13°C (10°F) and maximums reaching 7°C (46°F). Expect a significant amount of precipitation, with around 155 mm (6.1 in) falling over approximately 19 days. The air can feel quite dense, with an average humidity of 92% adding to the chill.
In December in Happy Valley, the average temperature is -1°C (31°F), with maximums reaching 7°C (46°F) and minimums potentially dropping as low as -13°C (10°F). Travelers should be prepared for cold weather and bring appropriate winter clothing if visiting during this time.
In Happy Valley in December, the total precipitation amount is 155 mm (6.1 in), which occurs over the course of 19 days.
In Happy Valley in December humidity is 92%. With an average temperature of -1°C (31°F), this humidity feels like a heavy, damp chill that seeps into your bones, making travel uncomfortable and challenging as the cold air mixes with the moisture, creating a biting sensation that lingers long after stepping outside.
In Happy Valley in December, the maximum UV index is 1, which corresponds to a low Exposure Category. This means you have a time to burn of 45 minutes. For more details, you can check the Hourly UV Index in Happy Valley.
UV Risk Categories
Weather in Happy Valley varies notably across the year, with each month offering distinct climate conditions. This page compares December’s weather to other months in Happy Valley, focusing on differences in temperature, rainfall, humidity, and UV levels.
| Temperature | Precipitation | Humidity | UV | |
|---|---|---|---|---|
| January Weather | -3°C (26°F) | 78 mm (3.1 inches) | 92% | low |
| February Weather | -2°C (28°F) | 70 mm (2.8 inches) | 92% | low |
| March Weather | -1°C (30°F) | 54 mm (2.1 inches) | 86% | moderate |
| April Weather | 3°C (37°F) | 51 mm (2.0 inches) | 79% | moderate |
| May Weather | 7°C (45°F) | 96 mm (3.8 inches) | 87% | high |
| June Weather | 10°C (51°F) | 64 mm (2.5 inches) | 91% | high |
| July Weather | 13°C (55°F) | 85 mm (3.3 inches) | 92% | high |
| August Weather | 13°C (56°F) | 99 mm (3.9 inches) | 92% | high |
| September Weather | 11°C (51°F) | 139 mm (5.5 inches) | 90% | moderate |
| October Weather | 6°C (44°F) | 164 mm (6.5 inches) | 87% | low |
| November Weather | 0°C (33°F) | 124 mm (4.9 inches) | 91% | low |
| December Weather | -1°C (31°F) | 155 mm (6.1 inches) | 92% | low |