Climate averages 1991–2020
Seattle weather
in December.
A cold, wet month: the coolest and the 11th driest of the year.
Long-term climate patterns, not a forecast for a particular trip.
December is a cold month in Seattle: daytime highs average 6.6°C and nights cool to about 1.6°C. By daytime temperature it is the coolest month of the year.
Expect about 178 mm of rain on roughly 18 days, which makes December a wet month (the 11th driest of the 12 months). Daylight, from sunrise to sunset, lasts about 8 h 31 min on an average December day.
The nearest other city in this atlas is Bellevue (10 km away). In December its highs average 6.8°C, about as warm as Seattle, with 178 mm of rain.
Among the 498 cities listed in the United States, Seattle ranks 317th of 498 for the warmest December highs and joint 481st of 498 for the driest December (rainfall, lowest first). The mean December high of those 498 cities is 10.5°C; Seattle is 3.9°C cooler than that mean.
From December to January, average highs rise by 0.6°C to 7.2°C, and monthly rainfall falls from 178 mm to 176 mm.
The annual picture
December in context
Monthly rainfall
Average total · mmAverages from hourly ERA5 reanalysis data. Actual weather varies from year to year. How these numbers are calculated
Every month, side by side
Seattle climate table
| Month | Average highHigh / low | Average low | Rainfall mm/month | Rain days ≥1 mm/day | Daylight hours/dayDaylight h/day |
|---|---|---|---|---|---|
| January | 7.2°C1.6°C | 1.6°C | 176 | 18.4 | 8.99 h |
| February | 8.6°C1.4°C | 1.4°C | 121 | 14.7 | 10.210 h |
| March | 10.8°C2.9°C | 2.9°C | 139 | 17.5 | 11.912 h |
| April | 13.4°C4.8°C | 4.8°C | 113 | 14.9 | 13.614 h |
| May | 17.1°C8.2°C | 8.2°C | 76 | 12.0 | 15.115 h |
| June | 19.7°C11.0°C | 11.0°C | 59 | 9.5 | 15.916 h |
| July | 23.7°C13.6°C | 13.6°C | 25 | 5.0 | 15.616 h |
| August | 24.0°C13.9°C | 13.9°C | 33 | 4.8 | 14.314 h |
| September | 20.6°C11.3°C | 11.3°C | 67 | 8.4 | 12.613 h |
| October | 14.6°C7.4°C | 7.4°C | 134 | 14.1 | 10.911 h |
| November | 9.6°C4.0°C | 4.0°C | 194 | 18.0 | 9.49 h |
| December, selected | 6.6°C1.6°C | 1.6°C | 178 | 17.7 | 8.59 h |
Rainfall is the average of the 30 separate monthly totals. A rain day is a local calendar day with at least 1 mm of precipitation. Daylight is the calculated sunrise-to-sunset length, not measured sunshine.
Compare places
December in nearby cities
- Bellevue in DecemberUnited States · 10 kmHigh 6.8°C · Low 1.7°C · 178 mm rain
- Kirkland in DecemberUnited States · 12 kmHigh 6.5°C · Low 1.8°C · 181 mm rain
- Renton in DecemberUnited States · 16 kmHigh 7.1°C · Low 1.8°C · 178 mm rain
- Kent in DecemberUnited States · 26 kmHigh 7.1°C · Low 1.9°C · 178 mm rain
- Federal Way in DecemberUnited States · 32 kmHigh 6.2°C · Low 1.1°C · 196 mm rain
- Auburn in DecemberUnited States · 34 kmHigh 6.8°C · Low 1.5°C · 196 mm rain
- Tacoma in DecemberUnited States · 40 kmHigh 6.7°C · Low 1.8°C · 174 mm rain
- Everett in DecemberUnited States · 43 kmHigh 6.4°C · Low 1.8°C · 231 mm rain
Read the numbers correctly
Climate, not a promise.
These patterns help compare months. They cannot tell you the weather on a specific day of your trip.
Sources, method and limitsHow these numbers are made (what the highs, lows and rain days mean, the sources and the model cell used for Seattle) is explained once on the Seattle year overview and on the Sources, method and limits page.
Bellevue, Kent and Renton lie in the same rainfall cell, so their rainfall figures are identical to these; temperatures differ because they come from smaller 0.1° cells.