Tropical Cyclone Harold is now a category three system with sustained winds of over 145 km/h.
The Fiji Meteorology Service said severe Tropical Cyclone Harold was continuing to intensify as it moves southeast at 14 km.
It said winds close to its centre were expected to increase to over 175 km/h.
The system was now affecting Vanuatu's northern group.
Tropical Cyclone Harold will be a powerful category 4 early tomorrow morning as it moves closer to Vanuatu.
A category 4 cyclone has winds of between 209-251 km/h.
Meanwhile 28 people were still missing from a Solomon Islands passenger boat which ignored maritime warnings and embarked on an island crossing in the middle of the cyclone.
The MV Taimareho left the capital Honiara on Thursday evening bound for West Are'are on Malaita.
Early Friday morning it encountered extreme weather conditions generated by Cyclone Harold and some of its passengers were swept overboard.
The Solomon Business Magazine reported a head count had been carried out onboard the ship and 28 people were unaccounted for.
A search and rescue operation was still underway.
The passengers were returning to the provinces as part of a national repatriation exercise ordered by the government as part of its Covid-19 preparedness strategy.
On Friday, the Director of the Director of the National Disaster Management Office, Loti Yates, said at least two ships had been washed ashore, fallen trees were blocking roads and the power was out in many areas.
Acting Police Commissioner, Mostyn Mangau, told the Solomon Star, that people need to take all precautions especially those living close to river banks to move to high grounds immediately.
"Do not try to cross rivers with an unknown depth. This is too risky. If the flood risk increases, make plans move to higher grounds. Do not allow children to play in the rain or near the rivers or along the drains," he said.
"I call on drivers do take extra care when travelling on wet, slippery and flooded roads and beware of water covered roads and bridges.
"Make sure you have your lights on and drive at low speed and do not attempt to cross flowing rivers and large streams of unknown depth."
"Mariners are advised to be extra caution when planning or travelling out in the sea. Avoid travelling at all if you can. When going out in the sea, always inform someone of where you are going and your expected time of arrival at your destination."
"Take extra fuel, paddles, life jackets, torchlight, spare batteries, water and some food when travelling." Acting Commissioner Mangau said.
"Stay on alert and watch out for landslides which could be caused by the continuing heavy rain especially those living on hillsides. Make sure you tie down any loose material that might be blown by the wind causing a danger to other people."
Vanuatu on alert
The Vanuatu National Disaster Management Office (NDMO) advises that Yellow Alert is now in effect for Torba and Sanma province.
Yellow alert forecasts a Cyclone within 12 hours and people needed to get ready and act now. The next level up is Red which means a Cyclone was imminent and that people needed to stay in shelter or a safe place.
The Vanuatu Meteorology and Geo-Hazards Department issued a Tropical Cyclone Warning for Torba and Sanma.
It said the provinces could expect strong winds, heavy rainfall and flooding over low lying areas and areas close rivers, as well as coastal flooding.
The neighbouring provinces Malampa, Penama and Shefa could expect similar bad weather tonight and tomorrow.
The Vanuatu National Disaster Management Office said people should listen to Radio Vanuatu and other radio outlets to get the latest update on this system.