Police are advising motorists to drive with care in the Bay of Plenty this morning with reports of black ice the roads.

There are reports of black ice on State Highway 5, in the Mamaku Ranges, and on State Highway 29, on the Matamata side of the Kaimai Range.

The sun is shining in the Bay but cold temperatures overnight have seen black ice form on the roads.

'Police have been advised of several crashes on SH5 across the Mamaku Ranges,” says a statement from Bay of Plenty Police.

'There are patches of back ice on the road. Road Crews are aware and heading into the area to spread grit.”

State Highway 47, between Turangi and Tongariro, is currently closed due to ice.

Police are asking motorists to find alternative routes or delay their journey until the road is opened.

"The conditions are still dangerous on our roads so please take care."

Colder temperatures are expected to remain from now until mid-August as the traditional winter months set in.

The MetService says people can expect to see overnight lows sitting anywhere from 5 degrees or lower and daily highs to be around the 15 degree mark.