People in Vanuatu are being warned to stay clear of flood zones with rising rivers, mudslides and sea swells predicted as Tropical Cyclone Oma hits northern provinces.
The category 2 cyclone is moving slowly, increasing the impact of heavy rains over Torba, Sanma, Penama and Malampa provinces.
The government has issued a red alert closing schools and businesses.
The Red Cross team leader on Santo island, John Boar, said people must stay at home.
He said the cyclone was already drenching the western parts of Santo and the rest of Sanma Province.
"Since it is moving very slow, we will experience more rain and flooding in the areas of Sanma," Mr Boar said.
"There's a lot of rivers we would expect more flooding and mudslides in areas where there are loose soil."
The cyclone is expected to affect the city of Luganville on the south of Santo on Thursday afternoon, Mr Boar said.
Meanwhile, the Vanuatu Meteorology Department, said Oma was located 50km west southwest of Santo and 200km southwest of Sola at 6pm local time.
Between 3pm and 6pm, the cyclone had moved in a southerly direction at 4km/hr, the department said.
Damaging gale force winds of 75 km/hr with gusts up to 100km/hr would continue to affect Torba and Sanma and Penama provinces for the next 12 to 24 hours, it said.
Storm force winds of 95km/hr gusting up to 130km/hr were also expected to affect the provinces tonight.
Seas are forecast to be very rough with phenomenal swells, prompting the department to advise people not to go out to sea until the system had moved out of the area.