State Highway One south of Kaikoura will be closed tonight.
NZTA say a portion of the highway will be inaccessible from 6pm because of heavy rain being forecast and the risk of small slips and rock-falls.
The road will be closed between Leader Road, north of Cheviot, and Peketa just south of Kaikoura.
The situation will be re-considered at 9am, but the Inland Road via Waiau is remaining open.
it comes after a heavy rain warning was issued this morning for the bottom of the North Island and top of the South.
MetService says downpours are expected about Wairarapa, the Tararua District, Marlborough including the Sounds, and the northwestern ranges of Nelson.
People in those areas are being advised streams and rivers could rise rapidly, driving conditions may be hazardous, and heavy rain could cause surface flooding and slips.