The storm destroyed nearly all buildings on the island of Barbuda on Wednesday, killing a two-year-old child as a family tried to escape, before wreaking havoc on the French territories of St Martin and St Barts, leaving at least seven dead.
Foreign Secretary Boris Johnson said the UK is “taking swift action to respond” to the disaster after speaking to the chief minister of Anguilla, a British overseas territory that was among the first islands to be hit.
A massive operation is under way to evacuate people away from coastal areas on Haiti and the Dominican Republic, where aid workers are moving residents into temporary shelters before Irma hits.
These are charities helping victims in need of donations.
A number of international charities have launched emergency appeals to help victims in the Caribbean and America. A number already have volunteers on the ground.
American Red Cross is working in Puerto Rico, the Dominican Republic, Haiti and Cuba and Florida.
Oxfam is on the ground in the Caribbean.
Convoy of Hope is working in the BVI and Haiti.
Unicef is working to help children affected by Hurricane Irma.
In the U.S.
The Salvation Army is on the ground in Florida to provide relief.
United Way Miami is helping victims of Hurricanes Harvey and Irma in the Miami area.
SPCA Florida is helping animals affected by Irma.
If you live near the area affected by Hurricane Irma, you can volunteer with the American Red Cross to help victims. Volunteers need to be able to commit to 10 hours a day for 10 days.