Weather forecaster Accuweather.com said that if Gustav passes through the Yucatan Channel into the Gulf, the storm could intensify into a Category 4 or 5 hurricane.
A powerful storm in the Gulf could force shutdowns on the offshore rigs that account for about a quarter of U.S. crude production and much of its natural gas. Royal Dutch Shell PLC said it could begin evacuating workers as soon as Wednesday.
Losses by the U.S. dollar against other major currencies also helped boost oil prices.
"We're getting some pretty powerful data that suggests slower growth and higher gasoline prices have really crimped oil demand in the U.S," Moore said.
Investors were waiting for an EIA report on U.S. oil stocks for the week ended Aug. 21 later in the day. The petroleum supply report was expected to show that gasoline inventories fell by 2.8 million barrels, according to the average of analysts' estimates in a survey by energy information provider Platts.