A hurricane warning is in place for the Tongan island groups of Vava'u and Ha'apai as Cyclone Wilma nears the kingdom.
The cyclone is moving south-southwest and is expected to lie 30 kilometres south of Vava'u by one o'clock this afternoon.
Cyclone forecaster with the Fiji Met Service, Teri Atalevu says heavy rain and strong winds gusting up to 160 kilometres per hour (90 knots) are forecast.
He says the cyclone is likely to bring flooding and heavy swells to parts of Tonga.
"Certain places are under hurricane warning. Some places are under storm, some are under gale warnings, and the rest of the group is under a strong wind warning. Flooding, including sea flooding for low-lying coastal areas, will be a problem."
Fjian Meterological service forecaster Teri Atalevu.