Cyclone Gita, which has already caused extensive damage and flooding in Samoa, is now strengthening to a Category-5 tropical cyclone and is due to hit Tonga today.
Tonga's Meteorological Service has issues a Hurricane Warning for Tongatapu and 'Eua, as well as damaging swell, heavy rain and flash flooding warnings.
"Very destructive hurricane force winds are expected from this evening," the service warns.
Category-5 storms are the top of the scale, with winds of more than 252kmh.
Cyclone Winston, a Category-5 tropical cyclone which formed in February of 2016, killed 44 people in Fiji, injured 126 more and destroyed or damaged 40,000 homes.
Forecasts are currently about half and half on whether the remnant of the storm will eventually make landfall in New Zealand next week.
Cyclone Gita has already caused extensive flooding an damage in parts of Samoa, after hitting the island nation on Saturday.