Last updated: June 24, 2025
In Grand Coulee, United States during December, the average temperature hovers around -2°C (29°F), with lows dipping to -19°C (-2°F) and highs reaching up to 16°C (60°F). Expect 57 mm (2.2 in) of precipitation spread across 11 days, contributing to an average humidity of 86%.
In December in Grand Coulee, the average temperature is -2°C (29°F), with a maximum that can reach 16°C (60°F) and a minimum that can plunge to -19°C (-2°F). It's advisable to pack for a wide range of temperatures when traveling during this month.
In Grand Coulee in December, the precipitation amount is 57 mm (2.2 in) spread over 11 days.
In Grand Coulee in December humidity is 86%. With an average temperature of -2°C (29°F), this humidity feels like a damp chill that seeps through layers of clothing, making outdoor activities uncomfortable and travel plans challenging.
In Grand Coulee 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 Grand Coulee, you can visit Hourly UV Index in Grand Coulee.
UV Risk Categories
Weather in Grand Coulee varies notably across the year, with each month offering distinct climate conditions. This page compares December’s weather to other months in Grand Coulee, focusing on differences in temperature, rainfall, humidity, and UV levels.
| Temperature | Precipitation | Humidity | UV | |
|---|---|---|---|---|
| January Weather | -2°C (28°F) | 67 mm (2.6 inches) | 85% | low |
| February Weather | -2°C (28°F) | 47 mm (1.9 inches) | 86% | moderate |
| March Weather | 4°C (39°F) | 46 mm (1.8 inches) | 86% | moderate |
| April Weather | 9°C (48°F) | 39 mm (1.6 inches) | 82% | high |
| May Weather | 15°C (59°F) | 37 mm (1.4 inches) | 77% | very high |
| June Weather | 20°C (68°F) | 13 mm (0.5 inches) | 79% | very high |
| July Weather | 24°C (75°F) | 4 mm (0.1 inches) | 77% | very high |
| August Weather | 23°C (74°F) | 8 mm (0.3 inches) | 62% | very high |
| September Weather | 17°C (62°F) | 24 mm (1.0 inches) | 60% | high |
| October Weather | 8°C (48°F) | 42 mm (1.7 inches) | 80% | moderate |
| November Weather | 3°C (37°F) | 51 mm (2.0 inches) | 87% | moderate |
| December Weather | -2°C (29°F) | 57 mm (2.2 inches) | 86% | low |