Heavy black clouds, thunder and a downpour which brought 13mm of rain to one site in the ranges north of Napier on Sunday afternoon was the first sign of a storm forecast for overnight.

A MetService spokesman said about 4.30pm the severe weather warning remained in place, with forecasts of 75mm to 100mm of rain in some places from Tutira north, at up to 35mm an hour in isolated places.

The warning, for the 15 hours from 6pm to 9am Monday would reviewed in the early evening, he said.

Thundery skies over Napier on Sunday. Photo / Paul Taylor
Thundery skies over Napier on Sunday. Photo / Paul Taylor

MetService warned that heavy rain may cause streams and rivers to rise rapidly. Surface flooding and slips are also possible and driving conditions may be hazardous.

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Strong to gale-force southerlies are also possible.

The remainder of Hawke's Bay was under a severe weather watch, the next level down from a warning.

A rain shower is dumped on Te Mata Peak, Havelock North. 75mm-100mm of rain is forecast this evening. Photo / File
A rain shower is dumped on Te Mata Peak, Havelock North. 75mm-100mm of rain is forecast this evening. Photo / File

The rains were part of an active trough moving north across central New Zealand this evening.

The heaviest rain is expected about eastern parts of Marlborough.

People were advised to keep up to date with the latest forecasts in case other areas are added to the warning.