The edge of the storm is expected to reach the area by early Saturday. The cap throttling the flow of oil will remain in place, unwatched for at least a few days.
The government's top official overseeing the spill, Thad Allen, says days of monitoring the temporary plug have convinced scientists it will hold.
Barring another setback - and the three-month operation has been filled with them - crude should never again gush from the infamous well.
Tropical Storm Bonnie, which blossomed over the Bahamas and was to enter the Gulf of Mexico by the weekend, could delay by another 12 days the push to plug the broken well for good using mud and cement, retired Coast Guard Adm. Thad Allen and BP officials conceded.
Even if it's not a direct hit, the rough weather will push back efforts to kill the well by at least a week.
"While this is not a hurricane, it's a storm that will have probably some significant impacts, we're taking appropriate cautions," Allen said in Mobile, Ala.
But a week of steady measurements through cameras and other devices convinced Allen they don't need to open vents to relieve pressure on the cap, which engineers had worried might contribute to leaks underground and an even bigger blowout. The cap was attached a week ago, and only minor leaks have been detected.
Crews will need up to 12 hours to disconnect the rig from the relief column.