Updated Dec. 7, 2018
During winter, we closely monitor snowpack as it builds in the mountains. The snowpack serves as a reservoir during the warm, dry months and feeds rivers and streams across the state. We will update this page with information about snowpack and related water supply conditions.
We’re off to a slow start for snowpack this year. However, it’s early in the season and there’s time to bounce back. More precipitation is expected in the coming weeks, although temperatures are likely to be warmer than usual January through March.
Snowpack & precipitation
Statewide mountain snowpack is at 38 percent of normal as of Dec. 7. The highest level is 77 percent of normal in the Walla Walla area. The lowest is 21 percent of normal in the Olympic Mountains.
Other parts of the Columbia River headwaters in Canada and Southeastern Idaho are seeing good snowpack.
Precipitation has been near or below normal. The state is about 1.7 inches below normal relative to the historical normal.
The U.S. Drought Monitor, a tool we use to assess water supply, still shows dry conditions across the state, which is a remnant of the warm and dry summer and fall.
October and November temperatures were near-normal to above-normal for most of the state, but it was even warmer in the mountains. October through November temperatures in the mountains were in the top 10 percent historically.
Looking ahead three to four weeks, the climate models suggest warmer-than-normal temperatures and more precipitation than normal.
For January through March, warmer-than-normal temperatures are expected but there isn’t consensus in the models regarding precipitation.
It’s looking more certain that the state will experience a weak or moderate El Nino starting in January, which generally means warmer and drier conditions for Washington.
Rivers & streams
The seven-day average streamflow statewide shows mostly normal flows for rivers, with some below-normal spots in southwest Washington and south Puget Sound. The daily mean streamflow is at normal and above at 47 percent of the 152 measuring sites across the state.