US crude oil prices fell more than $3 on Tuesday as traders discounted the possibility of storm disruptions, and were up $1 to over $104 a barrel on Wednesday after the OPEC producer group announced a surprise output cut.
New Orleans, still scarred by Katrina, which killed 1,500 people and caused $80bn in damage on the US Gulf Coast in 2005, appeared to be out of danger.
Ike's current track would see it hit the Texas coast just north of Corpus Christi, a major Gulf Coast oil refining hub.
But the storm's path is uncertain and officials in the port city of Galveston, just south of Houston, urged people living in flood-prone areas to leave.
At 1200GMT, the hurricane centre said in its latest advisory Ike was 145km north of the western tip of Cuba and about 695km southeast of the mouth of the Mississippi River.
It was churning northwest at 13kph, and was expected to veer west-northwest later on Wednesday.
Rainfall of up to 7.6cm was possible in the lower Florida keys, which could also face storm surges, large waves and isolated tornadoes and waterspouts on Wednesday, the centre said.
Southwest Florida was expected to see up to four 10cm of rain.
In Cuba, big waves and storm surges were expected to subside on Wednesday, but heavy rains on the western end of the island could produce flash floods, the centre said.
Ike has already caused widespread damage in Cuba.
Few official figures have emerged, but state-run media showed a panorama of destruction across the island, still reeling from the more powerful Hurricane Gustav ten days ago.
Ike struck eastern Cuba on Sunday with 195kph winds and torrential rains that destroyed buildings, wiped out the electricity grid, toppled trees, leveled crops including sugar cane fields, and turned rivers into roaring torrents.
After up to 40cm of rain fell on the island the downpour continued on Wednesday even as Ike moved away, causing widespread flooding and growing alarm among officials.
A total of 2.6 million people were evacuated before Ike, or about 22 per cent of the country's 11 million population, but officials said four people died in the eastern provinces.
Before Cuba, Ike hit Britain's Turks and Caicos Islands and the southern Bahamas as a ferocious Category 4 hurricane.
Floods triggered by its torrential rains were blamed for at least 71 deaths in Haiti, where Tropical Storm Hanna killed 500 people last week.