"The current containment system at the blowout location cannot handle a hurricane," he said. "It is rigidly fixed in place, and cannot flex to handle a hurricane's waves."

Masters noted that a hurricane has never passed over a massive oil spill before, so what actually would happen is uncertain.

The closest call: For 10 months, starting in June 1979, Ixtoc, an exploratory oil well, dumped 126 million gallons of oil into the Southern Gulf of Mexico. In September of that year, Category 1 Hurricane Henri swirled just north of the spill, producing high seas and gale force winds.

The wind converted the oil into a thick "mousse," he said, but the hurricane also scrubbed clean some oil-fouled beaches. NOAA found Henri's winds didn't blow long enough to influence the direction of that spill.

NOAA said a change in currents has greatly reduced the risk of oil reaching the Keys. The latest trajectory maps put the slick no closer than 385 miles from Key West.

However, that could change if a hurricane's winds blow strong and long enough, experts said. Potentially, the oil could end up in the loop current and be carried around the tip of the state and along the East Coast.

"All bets are off with a hurricane," Masters said.

He said that because of currents, it would take "just the right hurricane" to drive oil to the Keys. However, in September the currents likely will create a "relatively clear path for oil to follow to the Keys."

Both Masters and NOAA scientists say a hurricane would not result in oil mixing in with rain.

"Hurricanes draw water vapor from a large area, much larger than the area covered by oil, and rain is produced in clouds circulating the hurricane," NOAA said.