Average Ocean Temperatures for Alaska
Ocean temperatures off Anchorage in southern Alaska vary remarkably from summer to winter.
During most of winter, the sea temperature at Anchorage hovers just below the freezing point of fresh water. But over the long northern days of summer, water in Anchorage's sheltered inlet of Knik Arm warms rapidly. Surprisingly, these Alaskan waters become warmer in summer than those along the Pacific coast of central California.
Compared with Anchorage, the sea at Juneau in southeast Alaska doesn't get as cold in winter nor as warm in summer. Still, during July and August, the water there usually isn't much cooler than water at beaches much farther south.
National Oceanographic Data Center. NODC Coastal Water Temperature Guide (CWTG).