The specific configuration of the peninsula, extending westward into the path of Pacific storm systems, creates a rain shadow effect in reverse: the western slopes of the Olympic Mountains are among the wettest places in North America outside of the Pacific Coast rainforests of Alaska and British Columbia.

At Cape Alava, the annual precipitation is substantial, though not at the extreme levels of the mountain slopes immediately inland.

The constant presence of moisture, the frequent fog, and the characteristic overcast conditions of the outer coast create an environment in which organic material on the surface decomposes rapidly, but in which waterlogged conditions can be maintained indefinitely in subsurface deposits.

This hydrological character of the site was essential to the preservation of the Ozette materials.