Tropical Storm Eta has hit Florida, bringing with it heavy rain and strong winds that forecasters fear may lead to storm surges and flash flooding.
Schools, beaches and public transport in the southern part of the US state were shut before Eta made landfall late on Sunday in the Florida Keys.
With winds of up to 65mph (105km/h), Eta is moving westwards and is expected to strengthen over the Gulf of Mexico.
Eta has already wreaked devastation in parts of Central America.
About 200 people are reported to be dead or missing after Eta – earlier classified as a hurricane before losing strength – ripped through Panama, Honduras and Guatemala. It also passed through Cuba before making landfall in Florida.
In a statement, Britain’s Queen Elizabeth II said: “Prince Philip and I were deeply saddened by the tragic loss of life and destruction caused by Hurricane Eta.
“Our thoughts and prayers are with those who have been injured or lost their lives, and all those whose homes and livelihoods have been affected.”
What’s the latest on Eta?
The National Hurricane Center (NHC) warned in the early hours of Monday that “life-threatening flash flooding will be possible across inundated urban areas of south-east Florida”.
It said “flash and urban flooding will also be possible for Jamaica, the Bahamas, and the remainder of southern and eastern Florida over the next several days”.
“Some strengthening is forecast during the next day or so, and Eta is forecast to become a hurricane when it moves over the south-eastern Gulf of Mexico,” the NHC said.
In preparation for Eta, officials in Miami-Dade and Broward Counties, and in the Keys, ordered the closure of all schools, beaches and public transport. Mobile home parks and campgrounds in low-lying areas were also evacuated and shelters open.
“Please take this storm seriously,” Palm Beach County Emergency Management Director Bill Johnson urged residents, adding: “Please don’t drive through flooded roadways.”
Tens of thousands of people were evacuated in Cuba ahead of the arrival of Eta amid warnings of “significant, life-threatening flash and river flooding”. However, state media reported that there had been “no loss of life or significant damage to homes”.
Other parts of the region have not been so lucky.
Some 150 people are dead or missing in Guatemala after dozens of homes were buried by mudslides in the central region of Alta Verapaz. In neighbouring Honduras, at least 10 deaths have been confirmed, with hundreds of people reportedly waiting to be rescued from flooded areas.
Panama has reported 17 deaths and 68 people are missing, Security Minister Juan Pino said. In Mexico, officials in the southern state of Chiapas said the storm had claimed at least 20 lives.