Forecasters in Fiji are warning Tropical Cyclone Ian is again threatening Tonga.
In the latest advisory, Tropical Cyclone Ian has estimated winds of 65 knots, with gusts up to 90 knots.
It is expected to intensify and is moving east towards Niaufo'ou and Vava'au, but is expected to turn south-east in the next 6-12 hours.
Sanjay Prakash, a forecaster from the Fiji Meteorological service, told the cyclone has become stronger overnight.
"Ian has intensified...it's become a category three system," he said.
"It is expected to intensify further and probably reach its maximum intensity by tomorrow."
The Tonga Met office says on its current track, Tropical Cyclone Ian may bring gale force winds to Niaufo'ou in the next few hours, and Vava'a in the next 18-24 hours.
"It will be at its peak during the time of the landfall, I expect it to be at maximum intensity on the category three stage, that is having a sustained wind speeds of close to 85 knots at its centre," Mr Prakash said.
He says the cyclone will be "catastrophic" and "bring a lot of damage to the kingdom".
Earlier this week, a cyclone alert was issued for the island groups of Ha'apai and Vava'u with warnings of gale force winds, heavy rain, squally thunderstorms and the risk of sea flooding.
The alert was cancelled yesterday.
However, both the Fiji Meteorological Service and the Tonga Meteorological Service have since issued new warnings on Wednesday.
Ian has been hovering in the ocean between Fiji and Tonga since Monday.
A tropical cyclone alert and wind warning has also been issued for the northernmost group of islands of Tonga, the Niuas.
The slow moving cyclone may also cause thunderstorms, rough seas and some flooding in other parts of Tonga on Friday.
© ABC 2014
15:55 EDT Top Enders are being urged to not be complacent on the first official day of the tropical cyclone season.