Residents have been allowed to return to some islands in the hurricane-slammed Florida Keys as officials try to piece together the scope of Irma's destruction and rush aid to the drenched and debris-strewn state.
Two days after the storm roared into the Keys with 130mph winds, the full extent of the destruction is still a question mark because communications and access are cut off in many areas.
The Lower Keys - including the chain's most distant and most populous island, Key West, with 27,000 people - are still off-limits, with a roadblock where the single highway to the farther islands was washed out.
Seven deaths in Florida have been blamed on Irma, along with two in Georgia and one in South Carolina. At least 35 people were killed in the Caribbean.
SCIAF said it will respond to the needs of people worst hit by the storm and are urgently in need of donations to make sure people have access to clean water, food and shelter.
Haiti, the poorest nation in the western hemisphere, is one of the areas badly affected with damage to infrastructure and flooding. It was one of the most vulnerable islands in the path of Irma.
The Scottish charity said has a long-standing relationship with the people of Haiti and has been helping families rebuild their lives, especially after the deadly earthquake in 2010 and Hurricane Matthew last year.
SCIAF's head of communications, Charlotte Hull, said the charity is already on the ground in Haiti but relief efforts need to be international otherwise the situation could get worse.
She added: "We are part of the Caritas global network and will continue to assess the situation in the poorer areas affected by this latest catastrophe.
"A lot of the places where we work, Haiti in particular, are very rural and so we are struggling to get detail of the full extent of the situation because of the damage to communications and infrastructure.
"We need to make sure everyone understands the human impact of something like this and that we can all do our bit to help our brothers and sisters devastated by this latest hurricane and help them to build their resilience for when the next hurricane strikes."
