HONOLULU (Reuters) - Hurricane Flossie headed west toward Hawaii on Saturday, but the powerful Pacific storm was set to weaken and produce little more than heavy showers and high surf across the state early next week, forecasters said.

Flossie was now a Category 4 storm with maximum sustained winds of 130 mph (210 kph), up from 115 mph (185 kph) on Friday evening, according to the National Weather Service.

On its current course, Flossie would pass some 150 miles south of Hilo, Hawaii, by late on Tuesday said Roy Matsuda, lead forecaster with the weather service in Honolulu.

Winds at that point were expected to diminish to 65 mph (105 kph).

Hawaii has not experienced a hurricane since September 1992 when Hurricane Iniki, the most powerful hurricane to hit the volcanic islands in a century, struck Kauai. It killed three people, injured more than 100 and caused US$3 billion in damages.

"We expect as it gradually approaches the islands that it should weaken," Matsuda said. "It's going into cooler waters and into a shearing environment. That weakens hurricanes."

Flossie is the fifth hurricane to form in the Pacific Ocean this season, which runs from June 1 to November 30. Only two of those storms have approached the island chain.