Motorists were being urged to take an alternative route to State Highway 29 over the Kaimai Ranges in the Bay of Plenty if possible, as ice remained on the road.
The highway was closed for several hours on Saturday morning as roading contractors decided it was too dangerous for traffic.
Black ice on rural and urban roads in the Taupo area also prompted a police warning to motorists to drive carefully. They say Hatepe Hill and Pohipi Road are particularly affected.