A warning is in force for the State of Yap in the Federated States of Micronesia, as the US National Weather Service says Typhoon Maysak could become a super-typhoon today.
Damaging winds of over 230 kilometres per hour are expected to intensify into tomorrow.
The FSM government says five people are believed to have died when Maysak struck Chuuk state on Sunday, and there is severe damage to infrastructure and crops.
The typhoon is now 545 kilometres from Yap and 475 kilometres from Guam, and is expected to gradually intensify into a super typhoon, with tropical storm force winds extending outwards up to 200 kilometres north and 175 kilometres south of the epicentre.
The eye of the storm at 10pm UTC, and 8am in Yap, was near latitude 9.4 north and longitude 143.7 east, and moving west-northwest at 23 kilometres per hour.