Road access to Kaikoura will be cut off overnight.

Heavy rain has closed all roads to the coastal town - State Highway One and the Inland Route 70 via Mount Lyford.

An update on road conditions will be given at 9.30am tomorrow, once crews have been able to fully inspect the road.

NZTA is advising drivers to take extra care on all roads in the region, given the likelihood of surface flooding, rockfalls and small slips.