Farmers in the upper South Island are assessing the damage on Thursday, caused by more heavy rain overnight.
Heavy rain caused road closures, raging rivers and flooding across the Nelson and Tasman region on Wednesday.
Graham Ball, who farms in the Pupu Valley in Golden Bay, says 350mm had fallen on his dairy farm by Wednesday night, causing his creek to blow out.
He says one of his culverts is also blocked by a large slip and other debris is spread across his farm from the rising Takaka River.
He says it's the highest he's seen the river in about 20 years.
Mr Ball, who's also Federated Farmers Golden Bay president, says farmers moved stock to higher ground on Wednesday night and were braced for more steady rain.
MetService says the rain is not expected to ease until midday on Thursday.
Heavy rain warnings are also in place on Thursday for Mt Taranaki, Northland, north of Auckland, Coromandel Peninsula, Bay of Plenty and Tongariro National Park.