Heavy rain is set to lash parts of the South Island for much of Friday.
Orange level warnings are in place for Westland and Buller Districts until the evening.
MetService's Heath Gullery told Morning Report the rain was starting in the west of the South Island and slowly moving up to the lower North Island throughout Friday.
"There is likely to be some localised flooding, and rivers and streams will be running high."
Gullery said once the current rain front moved away there was more wet weather behind it, through until Tuesday next week.
However the temperatures would also be more mild, with the east of the North Island possibly reaching the low 20s.
"It's a change from that really cold weather we've had... It certainly will feel spring like."
And it might be some good news for hydro lake levels which have been blamed for soaring power prices.
"I think it will, it will be a gradual impact... it'll probably take several rain events to bring those levels up again," Gullery said.
Watches and warnings in place
Heavy rain warnings for Tasman, the Tararua Ranges and Mt Taranaki have been upgraded to orange.
MetService said up to 250mm of rain was expected on the Westland ranges and up to 100mm nearer the coast.
"Peak rates of 15 to 25 mm/h expected about the ranges during Friday," MetService said of Westland.
In Buller peak intensities of 10 to 15 mm/h were expected.
"Streams and rivers may rise rapidly. Surface flooding, slips, and difficult driving conditions possible."
Yellow strong wind watches are in place for Canterbury High Country, and Wellington.
Yellow heavy rain watches are in force for Richmond, Grey District and Fiordland.
Part of SH73, between Arthur's Pass Village and Otira, was closed on Friday morning due to rockfall, there were no detours available.