Residents from Greymouth were evacuated from their homes after heavy rain battered the South Island's West Coast on Monday.
Grey District Mayor Tony Kokshoorn says an intense downpour lasting about 90 minutes caused knee-deep flooding at seven houses in Murray Street.
Mr Kokshoorn says most of the houses were council-owned pensioners' cottages and 11 residents were spending the night in a motel.
Flood waters have also flowed through several shops and the Revington's Hotel in the town's central business district.
The Grey River remains at its usual level and its flood wall is not threatened by the heavy rains, he says.
MetService says a front over Westland is moving slowly north. Rain in Buller, the ranges of Nelson and western Marlborough will become heavy from Monday night, with 200mm expected until Tuesday evening.
Westland and Fiordland have been hit by more than 11,000 lightning strikes since Sunday night.
Part of SH6 closed
Police are urging motorists on the West Coast to stay home, as heavy rain is causing flooding and slips.
State Highway 6 is closed at Fourteen Mile Creek between Greymouth and Westport on Monday night.
Police say motorists who need to travel overnight will have to take the inland route between the towns.
They are advising motorists to be careful elsewhere on the West Coast due to heavy rain, swollen rivers and rock falls.