Along the West Coast, powerlines were downed, hundreds of trees were toppled and power was out for many people.
A West Coast resident says the wild weather ripped the roof off a neighbour's shed and knocked over a tree.
Colin Kaldenbach from Paroa, just south of Greymouth, said for about two hours this afternoon the area was pelted by horizontal rain and driving wind.
Mr Kaldenbach said the howling noise from the wind was so loud that they didn't hear either the shed roof or tree coming down, but only realised when they saw the debris.
"We had to bring in everything that wasn't nailed down, or it was literally going flying," said Mr Kaldenbach.
His home was also without power for several hours during the worst of the storm, but that has now been restored.
He said the conditions had improved by around 2pm, but rain was still falling steadily.
Greymouth's town centre was cordoned off and sandbags were in place.
State Highway 6 between Hokitika and Haast as well as the stretch of the highway between Westport and Greymouth were closed.
In the Nelson region, about 50 people were evacuated from homes and campsites in low-lying coastal areas.
The airport was closed because of flooding and several roads have also been closed. The Red Cross had activated its disaster relief and welfare teams in the area.