Wild weather overnight is keeping two main South Island highways closed

State Highway 77 at Mt Hutt is shut because of fallen trees, and further south, State highway 94 in the Milford Sound is closed because of the avalanche risk.

Waka Kotahi journey manager Tresca Forrester says fortunately most main highways have avoided severe damage.

But she's asking drivers to take care as crews clean up.

Forrester says there'll also be workers out and about cleaning up the local council roading networks.