Southern Police are urging drivers to take extra care on the roads over the next few days.

"We have had a number of frosts in consecutive days across the south, and more icy conditions are expected in the coming days," Southern District road policing manager Inspector Craig Brown said.

"There are several areas where black ice has formed, and we are asking people to be cautious so that they reach their destination safely."

Inspector Brown said surface conditions are dangerous, especially in shaded areas and on bridge decks/surfaces.

"Icy roads are unforgiving, especially here in the South where we deal with some of the most intense winter conditions in the country."

He advised motorists to check weather conditions, and the NZTA Journey Planner, before setting out, and plan extra time for travel.