Large swells, coinciding with a high tide, have washed rocks and debris onto the road on Wellington's South Coast.
The Wellington City Council said some of the waves had crossed the road and entered properties.
MetService forecaster Nick Zachar said the four metre waves were being generated by a low pressure system to the South East of the country.
"We do have southerly swells of three and a half metres in Cook Strait and maximum wave height of about five metres or so, so it is a downward trend from about now."
The road between the eastern end of Lyall Bay to Moa Point Road is closed and the airport tunnel is partially flooded.
Front of house staff member at Maranui Cafe in Lyall Bay, Anna Brimer, said the waves had washed over the roads.
She said although the sea hit the building the cafe is in there had not been any damage.
Police said the swells were also affecting the Wairarapa coast and Cape Palliser road was closed.
Last month swells that were up to nine metres high off the Wellington coast forced the closure of Moa Point Road to the airport and Owhiro Bay Parade after sand, seaweed, driftwood and rocks were flung from the surf.