State Highway 2, through the Karangahake Gorge, is open to one lane.

A slip came down on the highway on Tuesday, forcing roading authorities to close the road.

Waka Kotahi NZ Transport Agency reports this morning that the road is open to one lane under sto/go traffic management.

People are being urged to drive with caution.

Those wanting to use an alternative route can useSH27 and SH29 via Kaimai Range for south. For north, use SH25 Coromandel.

"Please note, due to adverse weather motorists are advised to consider delaying their journey if possible," says a spokesperson for the roading agency.