Climate averages 1991–2020
Tri-Cities weather
in December.
A cold, fairly dry month: the coolest and the wettest of the year.
Long-term climate patterns, not a forecast for a particular trip.
December is a cold month in Tri-Cities: daytime highs average 5.6°C and nights cool to about -1.2°C. By daytime temperature it is the coolest month of the year.
Expect about 35 mm of rain on roughly 8 days, which makes December a fairly dry month (the wettest month of the year). Daylight, from sunrise to sunset, lasts about 8 h 41 min on an average December day.
The nearest other city in this atlas is Kennewick (6 km away). In December its highs average 5.4°C, about as warm as Tri-Cities, with 35 mm of rain.
Among the 498 cities listed in the United States, Tri-Cities ranks joint 337th of 498 for the warmest December highs and joint 66th of 498 for the driest December (rainfall, lowest first). The mean December high of those 498 cities is 10.5°C; Tri-Cities is 5.0°C cooler than that mean.
From December to January, average highs rise by 0.4°C to 6.0°C, and monthly rainfall falls from 35 mm to 34 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
Tri-Cities climate table
| Month | Average highHigh / low | Average low | Rainfall mm/month | Rain days ≥1 mm/day | Daylight hours/dayDaylight h/day |
|---|---|---|---|---|---|
| January | 6.0°C-1.5°C | -1.5°C | 34 | 8.1 | 9.19 h |
| February | 9.3°C-0.3°C | -0.3°C | 23 | 6.2 | 10.310 h |
| March | 14.3°C2.8°C | 2.8°C | 24 | 5.9 | 11.912 h |
| April | 19.3°C6.6°C | 6.6°C | 17 | 4.9 | 13.514 h |
| May | 25.0°C11.5°C | 11.5°C | 18 | 4.5 | 15.015 h |
| June | 28.9°C15.3°C | 15.3°C | 13 | 2.8 | 15.716 h |
| July | 34.2°C19.2°C | 19.2°C | 3.8 | 1.0 | 15.415 h |
| August | 33.2°C18.6°C | 18.6°C | 4.2 | 1.0 | 14.214 h |
| September | 27.5°C14.0°C | 14.0°C | 6.9 | 1.8 | 12.613 h |
| October | 18.9°C7.9°C | 7.9°C | 22 | 5.0 | 11.011 h |
| November | 10.7°C2.3°C | 2.3°C | 29 | 7.3 | 9.59 h |
| December, selected | 5.6°C-1.2°C | -1.2°C | 35 | 8.4 | 8.79 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
- Kennewick in DecemberUnited States · 6 kmHigh 5.4°C · Low -1.4°C · 35 mm rain
- Yakima in DecemberUnited States · 108 kmHigh 2.5°C · Low -4.0°C · 66 mm rain
- Spokane in DecemberUnited States · 207 kmHigh 1.9°C · Low -4.1°C · 78 mm precipitation
- Spokane Valley in DecemberUnited States · 217 kmHigh 1.7°C · Low -4.3°C · 85 mm precipitation
- Auburn in DecemberUnited States · 259 kmHigh 6.8°C · Low 1.5°C · 196 mm rain
- Kent in DecemberUnited States · 263 kmHigh 7.1°C · Low 1.9°C · 178 mm rain
- Gresham in DecemberUnited States · 264 kmHigh 6.8°C · Low 1.0°C · 244 mm rain
- Federal Way in DecemberUnited States · 266 kmHigh 6.2°C · Low 1.1°C · 196 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 Tri-Cities) is explained once on the Tri-Cities year overview and on the Sources, method and limits page.
Kennewick lies in the same rainfall cell, so its rainfall figures are identical to these; temperatures differ because they come from smaller 0.1° cells.