Last updated: June 24, 2025
In Umatilla, United States, the average temperature in December hovers around 17°C (62°F). Expect variable weather, with a minimum temperature dipping to 0°C (31°F) and a maximum reaching a warm 29°C (84°F). Prepare for some rainfall, as there is an average precipitation of 71 mm (2.8 in) over approximately 8 days. Plus, the average humidity is on the higher side at 84%, ensuring that you'll feel the moisture in the air!
In December in Umatilla, the average temperature is 17°C (62°F), with maximums reaching up to 29°C (84°F) and minimums dipping as low as 0°C (31°F). This makes it a perfect time for travelers to experience a diverse range of weather, suitable for both outdoor adventures and cozy indoor activities.
In Umatilla in December, the precipitation amount is 71 mm (2.8 in) over the course of 8 days.
In Umatilla in December humidity is 84%. With an average temperature of 17°C (62°F), this humidity feels like a warm blanket enveloping you, making travel both comforting and slightly stifling, as you navigate through a haze of thick, moisture-laden air.
In Umatilla in December, the maximum UV index reaches 5, which corresponds to a moderate Exposure Category. Under these conditions, the estimated time to burn is approximately 30 minutes. For more details, you can check the Hourly UV Index in Umatilla.
UV Risk Categories
Weather in Umatilla varies notably across the year, with each month offering distinct climate conditions. This page compares December’s weather to other months in Umatilla, focusing on differences in temperature, rainfall, humidity, and UV levels.
| Temperature | Precipitation | Humidity | UV | |
|---|---|---|---|---|
| January Weather | 15°C (59°F) | 47 mm (1.9 inches) | 83% | moderate |
| February Weather | 18°C (65°F) | 57 mm (2.2 inches) | 80% | very high |
| March Weather | 19°C (67°F) | 25 mm (1.0 inches) | 75% | very high |
| April Weather | 22°C (72°F) | 80 mm (3.2 inches) | 70% | extreme |
| May Weather | 25°C (77°F) | 97 mm (3.8 inches) | 68% | extreme |
| June Weather | 27°C (81°F) | 190 mm (7.5 inches) | 75% | extreme |
| July Weather | 27°C (82°F) | 221 mm (8.7 inches) | 79% | extreme |
| August Weather | 28°C (82°F) | 203 mm (8.0 inches) | 81% | extreme |
| September Weather | 27°C (81°F) | 153 mm (6.0 inches) | 83% | extreme |
| October Weather | 25°C (77°F) | 80 mm (3.1 inches) | 81% | very high |
| November Weather | 19°C (67°F) | 58 mm (2.3 inches) | 82% | high |
| December Weather | 17°C (62°F) | 71 mm (2.8 inches) | 84% | moderate |