"Humanitarian needs will be enormous. Many people have lost their homes. Shelter, food and water are urgent priorities in Port Vila," the Red Cross twittered on Saturday.
Earlier in the day, the Vanuatu Meteorological Services said that "very destructive hurricane force winds" of 155 mile per hour (250 kilometers per hour) will rip through Shefa and Tafea provinces, while several others will face "very rough to phenomenal seas with heavy swells."
It added that the cyclone caused flash floods, knocking out telephone service all across Vanuatu.
The Joint Typhoon Warning Center in Hawaii, has, in turn, reported that Cyclone Pam had weakened from the equivalent of a Category 5 hurricane to a Category 4.
Meanwhile, the United Nations has said that it was preparing an rapid emergency response in Vanuatu.
At the same time, the United Nations said that it feared continued bad weather could prevent aid teams from deploying.
"Vanuatu is a very vulnerable place because of its location in the middle of the ocean. It's possible that there will be a death toll that could be high." the regional head of UNOCHA said.
Apart from Vanuatu, Cyclone Pam has also affected other Pacific nations, such as the Solomon Islands and Kiribati, where several homes were reportedly destroyed.