From the Coast Guard Historian's Office:

The U.S. Weather Observation Station Ship MUSKEGET (ex-CORNISH) departed Boston on the afternoon of 24 August, 1942, en route to Weather Station No. 2, 53°N - 42° 30'W. The first weather report from the vessel originated 28 August, 1942 while en route to her station. On 31 August, 1942 she reported on weather conditions. The last report on the weather was received from her 9 September, 1942, when she was awaiting the arrival of her relief, the USCGC MONOMOY. On 11 September 1942, the MONOMOY reported she was unable to effect relief of the MUSKEGET due to failure to establish communications. Enemy submarines were reported active and a message was transmitted by the MONOMOY for action of the MUSKEGET but the weather patrol vessel again failed to answer her call. Repeated efforts were made by the MONOMOY to contact the vessel without success. On 13 September 1942, the MONOMOY arrived at Weather Station No. 2 and cruised on station for 9 days. On 15 September 1942, upon a report from the MONOMOY of inability to communicate with the MUSKEGET, all aircraft and ships in the vicinity were directed to search for and report any positive results. This search on 16 September proved fruitless.

After a year had elapsed, Muskeget was presumed lost in action with no survivors. At the time of her sinking, she had 121 men on board: 9 commissioned officers, 107 enlisted men, one Public Health Service officer, and four civilian employees of the U.S. Weather Service. German naval records recovered after the war indicated that U-755, under the command of Kapitänleutnant Walter Göing, reported torpedoing a U.S. auxiliary merchant cruiser in Muskeget's area of operation on 9 September 1942. It was probably this attack that caused the destruction of Muskeget and the loss of her entire crew.