Hurricane Irma leaves Caribbean islands flooded and in darkness as it heads for Florida

San Juan, Puerto Rico

Hurricane Irma, one of the most powerful Atlantic storms in a century, churned across northern Caribbean islands on Wednesday with a potentially catastrophic mix of fierce winds, surf and rain, en route to a possible Florida landfall at the weekend.

Irma is expected to become the second powerful storm to thrash the US mainland in as many weeks but its precise trajectory remains uncertain.