Category five Hurricane Maria ravaged the island of Dominica after making landfall on 18th September, leaving 98 per cent of buildings damaged and thousands without power - affecting almost the entire 70,000 population.
After being downgraded to category four it then struck Puerto Rico.
Its 155-mph winds knocked out electricity to the entire island, leaving its 3.4 million people in the dark. It also triggered landslides and massive flooding as roads turned into raging debris-laden rivers.
Puerto Rico Governor Ricardo Rossello said: "There's a humanitarian emergency here in Puerto Rico. This is an event without precedent."
Samaritan's Purse has responded by sending a disaster assistance response team and emergency supplies to each island.
Generators have been flown to Puerto Rico to help residents dealing without electricity, a situation the charity said that may last for many months to come.
An 18-member volunteer group will arrive in Puerto Rico by the end of the weekend, bringing heavy-duty shelter plastic, hygiene kits, and more generators via Samaritan's Purse aircraft.
The charity said San Juan will continue to be the logistics hub for its multinational relief response across the Caribbean. A Samaritan's Purse team has been there for some time coordinating the Hurricane Irma response.
At least 30 people have died in Maria's wake throughout the Caribbean.
UK's International Development Secretary has announced on Sunday that the government will give Dominica £5 million in aid.