Temperatures ranged from , with high humidity. Rainfall was heavy, especially during the northwest monsoon season that ran until February. Air operations in this period could be mounted from Finschhafen but after February, the climate there was expected to restrict air operations, which would have to be conducted from Cape Gloucester. The climate dictated the timetable for the Cape Gloucester operation. In 1943, an Allied intelligence survey of the area estimated the local population around Cape Gloucester at around 3,000. There were numerous villages spread across four main areas: on the western coast, near Kalingi; on the western bank of the Itini River in the south; inland from Sag Sag and towards Tauali (on the western coast); and to the east of Mount Tangi, around Niapaua, Agulupella and Relmen. Prior to the Japanese invasion of New Britain in 1942, there had been two European missions around Cape Gloucester: a Roman Catholic mission at Kalingi and an Anglican one at Sag Sag.