Warm weather is continuing for parts of the North Island but in the south, West Coast locals are being told to prepare for heavy rain and possible flooding.
Civil Defence is monitoring the weather as MetService says an active front will bring heavy rain to parts of central and southern New Zealand.
Westland was expected to get exceptionally heavy rainfall, and flooding and slips were likely.
Westland Mayor Bruce Smith said the front could move through, or it could stall around the Franz Josef and Hari Hari area and cause major flooding.
He said all of the district's emergency operations centres had been set up in the event they were needed.
Hydrologists from the West Coast Regional Council are monitoring the situation and liaising with MetService.
Parts of Otago and Southland are also braced for heavy rain.
While the front is bringing severe weather to the South Island, in stark contrast farther north settled and warmer weather continues ahead of the front.
Temperatures along the East Coast in particular are set to reach the 20s today.
The highest temperatures forecast today are around Napier, expected to reach 29C.
Further up the coast at Gisborne temperatures are expected to hit 25C.
Similar temperatures are expected around Palmerston North and the Wellington region.
Christchurch will experience the hottest weather in the South Island, forecast to reach 26C.
Auckland and Northland temperatures will hover around the low 20s, with some light showers expected.
Showers are also expected across western areas of the North Island.