The Fua’amotu Tropical Cyclone Warning Centre has been activated as a tropical low north of Tonga's Vava'u islands is forecast to intensify and turn into a cyclone by tonight.
The system is then forecast to move in a south-easterly direction and be well clear of Tonga by Wednesday.
A Tropical Depression 03F was located 130km north-east of Neiafu, Vava’u, 190km south of Niuatoputapu and 430km north north-east of Nuku’alofa at 6am today.
The system is moving south south-west at about 10 knots (20km’hr).
TD03F is expected to move southwestwards towards the Vava’u group today.
Associated strong to gale force winds, cloudy conditions and periods of heavy rain and thunderstorms will affect the whole group today.
An extreme high tide and small craft advisory remains inforce for all of Tonga coastal waters.