(BIVN) – The National Weather Service in Honolulu has issued a High Wind Warning for Big Island summits, which is in effect from 6 p.m. Wednesday evening to 6 p.m. HST Thursday. A previously-issued High Wind Watch is no longer in effect.

Winds are forecast to increase to 40 to 60 mph Thursday atop Mauna Kea and Mauna Loa. A trough aloft is moving toward the Big Island from the northeast, increasing winds overnight.

Driving and hiking at the summits may be dangerous, forecasters say. Already, the road to the summit of Mauna Kea is closed to the public at the Visitor information Station at an elevation of 9,200 feet, rangers say, adding that the Maunakea Observatories Forecast posted strong (increasing) winds through Thursday afternoon, and that temperatures on the summit are below freezing.

A High Surf Advisory is also in effect for north-facing shores.