The Rimutaka Hill Road on State Highway 2 linking Wellington and Wairarapa will be closed for maintenance from 8pm on Wednesday.
The Transport Agency's regional performance manager, Mark Owen, says the road is closed for drainage maintenance that will finish on 12 February.
Mr Owen says traffic will be allowed through about every 30 minutes overnight, but asks motorists to put off unnecessary travel.
The road will fully reopen at 5.30am on Thursday.
