Key West, Fla. ? A hurricane watch was issued Sunday for the Florida Keys and Gov. Jeb Bush ordered a state of emergency in anticipation of Tropical Storm Ernesto.

Ernesto, which had strengthened into a hurricane for about 10 hours, weakened back into a tropical storm with top sustained winds of 50 mph by early evening, the National Hurricane Center said.

Still, the Miami-based hurricane center said the storm could reclaim its hurricane status before reaching the southeastern coast of Cuba this morning.

“It certainly looks like it’s going to impact a significant portion of Florida before it’s all over,” said Max Mayfield, director of the National Hurricane Center.

Florida has been hit by eight hurricanes in the past two years.

Officials in the Keys told tourists to postpone any immediate plans to travel there and ordered those already in the island chain to leave.

All travel trailers and recreational vehicles were ordered off the islands immediately. Residents were taking notice, too: a Home Depot store in Key West was busy Sunday afternoon as customers shopped for generators and other storm-preparation equipment.

“We put up the storm shutters today and we’re hitting the grocery store tomorrow,” said Ben Cassis, who, along with his father-in-law, spent nearly $2,500 for a powerful generator Sunday.

The state of emergency directs counties to open their emergency management offices and activates the National Guard, among other things. Bush canceled a scheduled trip to New York today, choosing to stay in Tallahassee and monitor storm developments.

Ernesto, the first hurricane of the Atlantic season, lashed Haiti and the Dominican Republic on Sunday. The storm was expected to arrive in southern Florida by early Tuesday, the National Hurricane Center said.

The low-lying Keys are connected to each other by just one highway, U.S. Highway 1. Traffic leaving the Keys on the single evacuation route was steady but not heavy Sunday afternoon.