The Mount Baker Snoqualmie National Forest is huge it stretches across the western slopes of the Cascade Mountains, from the Canadian border and North Cascades National Park to the northern boundary of Mount Ranier National Park. Surprisingly near Seattle, the landscape is harsh, dramatic, and rugged. It was cut out by the ancestors of the vast 10,000 acre glaciers that sprawl in the northern part of the forest. Mountain peaks over 10,000 feet plunge quickly into valleys at sea level. On top of all this, there is Mount Baker itself, which is still an active volcano; Sherman Crater emits steam and sulphur gases.
If you want to know what kind of weather to expect, well, that all depends on where exactly you're planning to be the climate varies dramatically within the forest. The Cascades create their own weather, pulling in Pacific Ocean storms. Huge masses of water-logged clouds come out of the ocean and slam into the mountain range most of the year. Valley bottoms, near the western edge of the forest, are typically dry, more Sierra-like in climate they receive only 30 to 60 inches of rain a year, while higher elevations recieve over 500, mostly in the form of snow. At higher elevations, 20 feet of snow on the ground is standard during the winter. In some areas, snow doesn't melt until midsummer.
Mount Baker Snoqualmie National Forest isn't kidding around, so be prepared it's a long, diverse area, breathtaking, tough, and promising enough to excite even the most jaded adventurers.