In Washington, beginning in May you can fish the first steelhead run in the Columbia or Snake River. Winter fishing for you can fish for trout is popular in Moses Lake and Lake Roosevelt, and for the later runs in rivers.
Summer run steelhead show up between May and July, and are a combination of wild steelhead and hatchery fish. The trout tend to be small because they were in the ocean for less time, but are known for an impressive fight when caught.
Steelhead that are released from hatcheries show up in November and are usually mid-range in size. They can be recognized by the lack of an adipose fin. The season for the hatchery run starts in early winter.
The winter run steelhead are usually significantly larger than the summer run or hatchery run fish, commonly weighing above 10 pounds. They show up in late winter, and are often lighter in color than the summer run steelhead.
Wild steelhead can be identified by the presence of a soft, fleshy adipose fin forward of the caudal fin. If you catch one, you must release it immediately. In Washington you may only keep four steelhead per day, and must report the details of your catch.