Based on 1,362 research-grade iNaturalist observations in Washington, California Sea Lion is most often recorded in April; in Washington it behaves like a spring and fall migrant. It ranks #19 among mammals recorded in the state in our data.
Zalophus californianus
California Sea Lion in Washington by month
Bars show research-grade observations per month. They mix true seasonality with how often people are outdoors, so treat small numbers with caution.
Also seen in Washington in April

Eastern Cottontail

Eastern Gray Squirrel
American Beaver
Douglas's Squirrel

Yellow-bellied Marmot

Common Raccoon

Harbor Seal

North American River Otter
Places to look in Washington
Gifford Pinchot National Forest
Olympic National Forest
Peace Arch Park
Colville National Forest
Mount Baker–Snoqualmie National Forest
Bellevue Botanical Garden
FAQ
When does California Sea Lion appear in Washington?
Mainly August–May, with the most records in April.
How common is California Sea Lion in Washington?
It ranks #19 by number of iNaturalist observations among mammals in Washington (1,362 records in our sample).