Residents were ordered to be evacuated from the lower Florida Keys on Monday as strengthening tropical storm Rita headed toward the island chain, threatening to grow into a hurricane with a potential 2.4-metre storm surge.
Although Rita's immediate threat was to Florida, rough projections of its track raised the possibility that the Louisiana coast could be targeted less than a month after Hurricane Katrina devastated the area.
Oil prices surged as traders worried about Rita's possible effect on facilities in the Gulf of Mexico.
The Keys evacuation covered 40,000 people. Visitors were ordered to clear out of the entire length of the low-lying Keys, which are connected by just one highway. Hurricane warnings were posted for the Keys and Miami-Dade County in Florida, and the storm's eye was expected to pass between the islands and Cuba on Tuesday, the National Hurricane Centre said.
Voluntary evacuation orders were posted for some 134,000 Miami-Dade residents who live in coastal areas such as Miami Beach and Key Biscayne.
Rita had sustained wind of 105 kph by late morning, up from 97 kph earlier in the day, and could be a category 1 hurricane by the time it passes Keys, the National Hurricane Centre added.
It is the 17th named storm of the Atlantic hurricane season, making this the fourth busiest season since record-keeping started in 1851. The record is 21 tropical storms in 1933.