Last updated: June 24, 2025
In December, the average temperature in Hermiston, United States hovers around 3°C (37°F), with an impressive temperature range from a chilly -13°C (9°F) to a warm 20°C (69°F). Expect about 40 mm (1.6 in) of precipitation spread over 10 days, and be prepared for a relatively high average humidity of 87%.
In December in Hermiston, the average temperature is 3°C (37°F). Maximum temperatures can reach 20°C (69°F), while minimums can drop as low as -13°C (9°F). Travelers should be prepared for a wide range of temperatures, ensuring they pack accordingly for both warm and cold conditions.
In Hermiston in December, the precipitation amount is 40 mm (1.6 in) over a span of 10 days.
In Hermiston in December, humidity is 87%. With an average temperature of 3°C (37°F), this humidity feels like a damp chill that clings to your skin, making outdoor activities uncomfortable and necessitating proper layers to stay warm while navigating the wet conditions.
In Hermiston 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 Hermiston, you can visit Hourly UV Index in Hermiston.
UV Risk Categories
Weather in Hermiston varies notably across the year, with each month offering distinct climate conditions. This page compares December’s weather to other months in Hermiston, focusing on differences in temperature, rainfall, humidity, and UV levels.
| Temperature | Precipitation | Humidity | UV | |
|---|---|---|---|---|
| January Weather | 2°C (37°F) | 40 mm (1.6 inches) | 86% | low |
| February Weather | 3°C (38°F) | 54 mm (2.1 inches) | 86% | moderate |
| March Weather | 8°C (46°F) | 40 mm (1.6 inches) | 85% | high |
| April Weather | 12°C (54°F) | 31 mm (1.2 inches) | 83% | high |
| May Weather | 18°C (64°F) | 17 mm (0.7 inches) | 77% | very high |
| June Weather | 22°C (72°F) | 10 mm (0.4 inches) | 81% | very high |
| July Weather | 27°C (80°F) | 0 mm (0.0 inches) | 76% | very high |
| August Weather | 26°C (79°F) | 5 mm (0.2 inches) | 60% | very high |
| September Weather | 20°C (68°F) | 12 mm (0.5 inches) | 58% | high |
| October Weather | 12°C (54°F) | 29 mm (1.1 inches) | 75% | moderate |
| November Weather | 6°C (44°F) | 39 mm (1.6 inches) | 85% | moderate |
| December Weather | 3°C (37°F) | 40 mm (1.6 inches) | 87% | low |