Last updated: June 24, 2025
In December, the average temperature in Marietta-Alderwood, United States hovers around 5°C (41°F). Be prepared for a range that can drop as low as -12°C (10°F) and rise to a maximum of 12°C (55°F). With an average precipitation of 227 mm (8.9 in) spread over 18 days, it's wise to keep an umbrella handy. Additionally, expect high humidity levels at around 87%, making the air feel cooler and more crisp.
In December in Marietta-Alderwood, the average temperature is 5°C (41°F), with maximums reaching up to 12°C (55°F) and minimums dropping as low as -12°C (10°F). Be prepared for chilly weather, and pack warm layers if you're planning to visit!
In Marietta-Alderwood in December, the precipitation amount is 227 mm (8.9 in) accumulated over 18 days.
In Marietta-Alderwood in December humidity is 87%. With an average temperature of 5°C (41°F), this humidity feels like a heavy, damp blanket enveloping you, making every step seem laborious and the chill more biting, which can be quite challenging for traveling.
In Marietta-Alderwood 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 Marietta-Alderwood.
UV Risk Categories
Weather in Marietta-Alderwood varies notably across the year, with each month offering distinct climate conditions. This page compares December’s weather to other months in Marietta-Alderwood, focusing on differences in temperature, rainfall, humidity, and UV levels.
| Temperature | Precipitation | Humidity | UV | |
|---|---|---|---|---|
| January Weather | 5°C (41°F) | 199 mm (7.8 inches) | 86% | low |
| February Weather | 4°C (39°F) | 185 mm (7.3 inches) | 85% | moderate |
| March Weather | 6°C (44°F) | 156 mm (6.2 inches) | 86% | moderate |
| April Weather | 9°C (48°F) | 127 mm (5.0 inches) | 86% | high |
| May Weather | 12°C (53°F) | 76 mm (3.0 inches) | 81% | very high |
| June Weather | 15°C (59°F) | 58 mm (2.3 inches) | 83% | very high |
| July Weather | 17°C (63°F) | 27 mm (1.1 inches) | 84% | very high |
| August Weather | 18°C (64°F) | 19 mm (0.8 inches) | 77% | very high |
| September Weather | 15°C (60°F) | 125 mm (4.9 inches) | 76% | high |
| October Weather | 11°C (51°F) | 186 mm (7.3 inches) | 88% | moderate |
| November Weather | 8°C (46°F) | 261 mm (10.3 inches) | 87% | low |
| December Weather | 5°C (41°F) | 227 mm (8.9 inches) | 87% | low |