Bart Jansen

USA TODAY

Forget the swimsuits for Hawaii and pack raincoats and winter parkas.

The National Weather Service issued a winter-storm warning until 6 p.m. Saturday local time, with heavy, flooding rainfall across the chain of Pacific islands and up to 30 inches of snow on the peaks of the Big Island.

Drifting snow, freezing fog and gusting wind are forecast for the summits of Mauna Kea and Mauna Loa volcanoes above 11,000 feet. Visibility could be less than a quarter-mile, making driving and hiking dangerous.

“A winter storm warning means significant amounts of snow,” the weather service said early Friday local time. “This will make travel very hazardous or impossible.”

A flash-flood warning was in effect across the entire state’s islands Friday morning through Sunday. Rain was falling at a rate of 3 to 4 inches per hour in Hilo, Puna and Kau districts. Heavy showers and thunderstorms are expected.

“Flash flooding is expected to begin shortly,” the weather service said.