State Highway 6 will be closed tonight at a slip site near Makarora.
Tonight's closure follows heavy rain which further destabilised some areas of the slip, the New Zealand Transport Agency said in a statement.
The closure will run from 7pm tonight until 7am tomorrow.
Central Otago area manager John Jarvis said the rain had exposed further debris at the highest point of the slip, about 100m above the highway, making it unsafe for motorists to use the road tonight.
"We understand these closures are disruptive. However, our contractors are doing their best to get on top of the situation in what is a particularly steep and challenging environment with volatile weather."
The overnight closures will be reviewed daily.
The road is open to single-lane traffic during the day, but motorists can expect minor delays while clearance work continues.
