The Fiji Meteorological Service said Tropical Cyclone Sarai was expected to head towards the Ha’apai Group.
It said the now Category 2 storm is intensifying as it moves down Fiji’s west coast.
The Tonga Met Services said TC Sarai was located near Tonga waters and was moving south at the speed of 13 knots (26km/hr). The maximum winds near the centre is about 50 knots (100 km/hr) with momentary gust of up to 60knots (120km/hr).
On its current track, TC Sarai is expected to lie at about 190km west-southwest of Nadi, Fiji by 4am early tomorrow morning.
Meanwhile, a trough of low pressure lies slow moving over Vava’u and the Niuas. Associated clouds with occasional rain and strong winds will affect the group today.
RNZ has reported that at 4pm Fiji time today, the cyclone’s centre was located 230 kilometres north-west of Nadi with wind gusts of upto 130 kilometres an hour.
It said the cyclone is moving south but will turn south-east, and on its forecast track will pass adjacent to the main island Viti Levu and then across Fiji’s southern islands, before heading towards Tonga’s Ha’apai Group.
Fiji National University has closed all campuses because of the storm and the Fiji Red Cross has implemented disaster preparedness plans.
It said large trees are reported to have been brought down in the Suva area blocking roads and flooding in the Northern Division and Rakiraki have caused road closures.
Travellers to, from and within Fiji should contact airlines or shipping companies to confirm details as there have been cancellations.
Forecasters say the storm is also threatening prolonged periods of rain and flooding in low lying areas.