Seattle Weather in December
United States · Oceanic climate · Data averaged from 2020-01-01 to 2024-12-31 (5 years)
December in Seattle sees average temperatures ranging from a low of 3.4°C (38.1°F) to a high of 7.9°C (46.2°F), with a mean of 5.6°C (42.1°F). Compared to the annual average of 11.3°C (52.3°F), this month is 5.7°C cooler than the yearly norm. Precipitation averages 188.6mm, making it approximately 92.0mm wetter than the monthly average of 97.0mm. The city receives an average of 3.4 hours of sunshine per day during December, with relative humidity averaging 84.0%. Wind speeds reach an average maximum of 21.5 km/h. Snowfall averages 7.4cm during December, which can affect travel plans and outdoor activities. For travelers, this month offers a temperature experience in Seattle, with wetter-than-average conditions compared to the rest of the year.
Seattle's reputation for rain is exaggerated but not entirely wrong. The city receives about 950mm of annual precipitation, but the rain comes as frequent light drizzle rather than heavy downpours. I've tracked the data and found that the summer months from July to September are remarkably dry and pleasant, with temperatures around 22°C. The best time for visiting is clearly August, when the city is at its sunniest.
December vs Adjacent Months
| Metric | November | December | January |
|---|---|---|---|
| Mean Temp | 7.5°C (45.5°F) | 5.6°C (42.1°F) | 5.5°C (41.9°F) |
| Rainfall | 171.0mm | 188.6mm | 218.1mm |
| Sunshine | 4.5 hrs | 3.4 hrs | 3.6 hrs |
| Humidity | 83.1% | 84.0% | 84.2% |
| Wind | 21.7 km/h | 21.5 km/h | 21.4 km/h |
| Rainy Days | 20.6 | 20.8 | 22.8 |
| Snowfall | 3.4 cm | 7.4 cm | 8.4 cm |
Seasonal Context
December falls in Winter in the Northern Hemisphere. Winter is the coolest season with the shortest daylight hours. For travelers visiting Seattle in December, the data indicates mixed conditions based on the combination of temperature, precipitation, and daylight hours.
Frequently Asked Questions
What is the average temperature in Seattle in December?
The average temperature in Seattle during December ranges from 3.4°C (38.1°F) to 7.9°C (46.2°F), with a mean of 5.6°C (42.1°F).
How much does it rain in Seattle in December?
Seattle receives an average of 188.6mm of precipitation in December, spread across approximately 20.8 rainy days.
What should I pack for Seattle in December?
Based on December weather data, pack warm layers, a medium jacket, and waterproof outerwear. Rain gear is essential — this month averages 188.6mm of precipitation.
Is December a good time to visit Seattle?
December is a cooler month, suitable for travelers who prefer mild weather and fewer crowds. Pack warm layers and enjoy indoor attractions.
Other Months for Seattle
Cities with Similar December Climate (Oceanic)
Data Source: Open-Meteo historical archive (2020-01-01 to 2024-12-31). Daily measurements aggregated into monthly climate normals. Coordinates: 47.61°, -122.33°. Timezone: America/Los_Angeles. Last updated: 2026-07-30.