The storm – which killed at least eight people as it tore through the Caribbean – has already hit the island of St Martin, where the President owns a lavish waterfront estate.
But Palm Beach county, where the President’s so-called “winter White House”, Mar-a-Lago, is located, has declared a state of emergency.
A golf course Mr Trump owns in west Palm Beach is also under threat, as are two more in the city of Doral and the coastal town of Jupiter.
“The threat of direct hurricane impacts in Florida over the weekend and early next week continues to increase,” the US National Hurricane Center said.
It added that Irma would likely drop to a category 4 storm when it made landfall in Florida.
Category 4 storms maintain maximum sustained winds of between 130 to 156 mph and can be deadly.
Hurricane Irma – in pictures
The status of Mr Trump’s 11-bedroom gated mansion on St Martin, which is up for sale, was unknown, although property in the area was devastated by the hurricane.
The islands airport suffered “huge damage”, according to Dutch prime minister, Mark Rutte, who said it rendered the island “unreachable”.