Hurricane Katrina gained power over warm Gulf of Mexico waters and headed for the US coast again after already killing seven people in southern Florida.
By 8am (1pm Irish time), the hurricane was 690km southeast of the mouth of the Mississippi River, with winds near 185kph. The storm was larger and more powerful than when it hit Florida's southeast coast on Thursday and was expected to swing gradually west-northwest, the National Hurricane Center in Miami said.
The projected path could see it come ashore anywhere between the storm-scarred Florida Panhandle and the Louisiana coast west of the low-lying and vulnerable city of New Orleans.
US oil and gas rigs are potentially in its path. Computer models pointed to a more westerly track, putting Katrina ashore on Monday near the Louisiana-Mississippi border.
"That's bad news for New Orleans and better news for us," said Florida's top meteorologist, Ben Nelson.
Katrina posed a great risk of flooding all along the northern Gulf coast. Some projections foresaw it becoming a Category 4 storm on the five step Saffir-Simpson scale by Monday - a potentially catastrophic hurricaen with 210 kph-plus winds capable of causing widespread damage.
Florida Governor Jeb Bush said residents in the Florida Panhandle would be ready, even as many of them had not yet been able to fully repair their homes after being struck by Hurricane Dennis last month or Hurricane Ivan last September.