Seattle, Washington weather in December

Averages from 2021–2025 (155 days of record).

Average high: 47°F
Average low: 39°F
Rainy days: ~20 per month
Total precipitation: 7.9 in
Warmest recorded: 58°F
Coldest recorded: 20°F

Expect December days in Seattle, Washington to top out around 47°F and cool to about 39°F overnight, with roughly 20 days of measurable rain across the month. In recent years December has ranged from 20°F to 58°F.

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Current Seattle, Washington forecast → · Historical data by Open-Meteo (ERA5).