Boreas was built for the United States Shipping Board as SS Yaquina in 1919 at Oakland, California, by the Moore Shipbuilding Company; renamed Boreas on 29 October 1921; acquired by the Navy on 6 December 1921 and laid up in reserve at the Philadelphia Navy Yard; commissioned in ordinary on 6 August 1940; towed to the Todd-Robbins Dry Dock and Repair Company in Brooklyn, New York, for reactivation; and placed in full commission on 24 March 1941.

The ship made ten round-trips between San Francisco and Pearl Harbor in 1942 hauling goods and material to rebuild and resupply the strategic naval base.

On 26 December 1942, Boreas departed San Francisco, bound for Nouméa, New Caledonia, and Espiritu Santo, to begin supplying advanced bases.

Returning to Pearl Harbor or San Francisco to refill her holds with needed supplies, Boreas provisioned many of the major islands and bases in the Pacific including Samoa; Funafuti; Kwajalein; Eniwetok; Tulagi; Guadalcanal; Guam; Saipan; Iwo Jima; Okinawa; Manus; Ulithi; Efate; Tarawa; Makin; Christmas Island; and Auckland, New Zealand.

Boreas generally steamed alone, only occasionally rating a small escort, but the store ship never suffered damage and rarely even saw an enemy.

Late in 1944, she salvaged cargo from Asphalt, a concrete storage barge that had grounded on a coral reef off Saipan during a severe storm.

On the final voyage to Japan, each officer and crewman received at least a Japanese rifle, bayonet and signal pistol as a war trophy.