A blizzard warning was extended until 6 a.m. Thursday for the summits of Mauna Kea and Mauna Loa. Snow on the mountains is common, but a blizzard is unusual.
Up to 8 inches of snow could accumulate above 11,500 feet, the National Weather Service said.
"Usually it’s just a dusting or up to an inch or 2," said weather service meteorologist Norman Hui. "Right now we have a pretty powerful winter storm."
Kimberly Zarate-Amaya can normally see the summit of Mauna Kea from her home in Mountain View, but dense fog Wednesday made it difficult to get a glimpse.
She was hoping to be able to take her kids up to Mauna Kea to see the snow, but the road was closed Wednesday because of icy conditions.
"Honestly the fact it’s coming at Christmas is what makes it exciting," she said. "How often we can say in Hawaii we have a white Christmas?"
Meanwhile, a high-surf advisory remained in effect until 6 p.m. Thursday for the north shores of Oahu, Kauai, Niihau, Molokai and Maui, with waves up to 15 feet.