In April, "Sigsbee" patrolled the entrance to Humboldt Bay until the 26th when she screened a convoy to Cape Cretin. After patrolling in the Guadalcanal area for several weeks, "Sigsbee" joined TU 53.1.14 to take part in the Marianas campaign. The destroyer bombarded the Guam beaches during the period 16 to 18 July as well as covering the underwater demolition teams (UDTs) on the beaches. She then joined the picket screen and remained off Guam until 3 August. "Sigsbee" returned to Humboldt Bay for a month and then joined TF 77, proceeded to Morotai Island, North Moluccas, and provided fire support for the landings on Cape Podangi in mid-September.