Roughly one-hundred miles to the west is Washington's Pacific coast, where the continental United States receives its highest rainfall. Because the Olympic Mountains stand between the coast and Whidbey Island, they catch much of the rain that pounds the coast all winter. Whidbey Island still receives abundant, if gentler, winter precipitation, which occasionally turns to snow. The northern half of Whidbey Island is well situated in the Olympic rainshadow, and averages less than 20 inches annually, while the southern half of the island receives 30 inches. The only streams are in the south, and these are small and intermittent.
Water is limited, particularly in the north.
Once heavily forested with gigantic Douglas fir, western hemlock and red cedar, the island is still fifty-eight percent forest, although little or no old growth remains. The southern portion of Whidbey Island is hilly, and contains the highest plateaus on the island. Garry oak grows near Oak Harbor, while red alder, maple, ash and willow grow in wet areas and at shoreline. Wolves and bears once lived on the Whidbey Island. Migrating waterfowl use the shoreline and wetlands for stopovers and for nesting and breeding.