the observed warm temperatures are higher and cover more of the northern Pacific than the PDO typically affects. For all but the Gulf of Alaska, the warm waters appear to lie in a relatively shallow layer near the surface. The cold near-shore conditions in the Pacific Northwest also don't match the typical PDO pattern.

Warm ocean temperatures favor some species but not others. For instance, sardines and albacore tuna often thrive in warmer conditions. Pacific Coast salmon and steelhead rely on cold-water nutrients, which they may have found recently in the narrow margin of cold water along the Northwest coast. But if the warmth continues or expands Pacific Northwest salmon and steelhead could suffer in coming years.