The massive storm has already caused widespread destruction on several island nations. The Prime Minister of Barbuda says the hurricane has "totally demolished" the island and levelled 95 per cent of buildings.
Life-threatening storm surges are expected to cause flooding as high as three metres near the coasts of some islands, while torrential rain may cause flash floods and mudslides.
Irma has passed just north of Puerto Rico and is forecast to remain a powerful category 4 or 5 hurricane as it moves towards the Dominican Republic, Haiti and Bahamas over the next couple of days. Communities are also on alert in Cuba and Florida, which is still reeling from the devastation of Hurricane Matthews.
While it's too early to know the full impact of this crisis, one thing is certain: children are in danger. The destruction, flooding and chaos of a hurricane can leave children extremely vulnerable to injury, family separation and water-borne diseases.
UNICEF prepared for the worst
UNICEF has pre-positioned emergency supplies of drinking water, unperishable food and medicines, ready for rapid response to the worst-affected communities.
Our teams are on standby with emergency kits - each packed with a bucket, soap, toothbrushes and paste, detergent and other everyday necessities that families will need to cope with the tough days ahead.
UNICEF is also keeping young people informed with expert advice and updates via our U-Report platform. In the last 24 hours, we've seen a surge of adolescents in Haiti and the Dominican Republic signing up to receive this vital information via their Facebook Messenger and other social media accounts.
When disasters strike, UNICEF can:
The Caribbean is one of the most disaster-prone areas in the world but UNICEF has been there for children since the 1950s and we've prepared for this terrible moment.
- Restore life-saving medical services, water and sanitation.
- Deliver emergency hygiene and nutritional supplies to families who have lost everything.
- Reunite separated children with their parents.
- Set up child-friendly spaces to keep children off the streets and away from danger.
- Provide counselling and psychosocial support for children suffering profound stress.
- Help children back to school and through every step of the long-term recovery.
We've been working with governments to reduce the risks of disaster, strengthen community resilience and build the Return to Happiness program, which helps children cope and recover from loss.