A Wellington City Council spokesman said the road will be closed until at least mid-morning.
Police said the closure will cause disruption for some people.
Two other large slips in Wellington are threatening two homes.
One of the homes, on Evans Bay Parade, is occupied by a group of students who've had to bunk down with friends and family.
And a family have had to move out of their home on Devon St, after a slip tore out the sewage connection.
Council spokesman Richard MacLean said sign-offs will be needed from geotechnical engineers before the occupants are allowed back home.
He said the council is erring on the side of caution, while there's still rain to come.
Meanwhile, the Rimutaka Hill Rd north of Wellington is now open, but people are being told to take extra care because of snow and ice.
A number of warnings about snow and ice on highways in the South Island remain in place.
In Otago, State Highway 87 is affected between Outram and Middlemarch.
In Canterbury, there are warnings between Twizel and Fairlie, and from Mount Cook to Pukaki.
On the West Coast strong winds are being felt along SH6 between Ross and Haast.
In the North island, the Napier-Taupo Rd and the Desert Rd are open and no further snow is expected.
Clear skies over the South Island meant it was a freezing night for many people.
Mount Cook plunged to minus 13.7 degrees, and Tekapo hit minus 12.
MetService duty forecaster April Clark says the spot where it's often coldest - Alexandra - went to minus 6.3.
Clark said Canterbury has a bit of cloud around so didn't get quite so cold.
In the North Island, it's been almost 4 below zero in Taupo and 3.5 under on the Desert Rd.
