The upper North Island is on alert with heavy downpours and thunderstorms set to lash the area on Thursday.
MetService said a low-pressure system is expected to move slowly across northern New Zealand over the next few days and into the weekend, directing moist northeast winds with several embedded fronts affecting northern and central regions.
Periods of heavy rain and possible thunderstorms are forecast for northern and eastern areas of the North Island and the northeast of the South Island, affecting areas that are already saturated from recent rain events.
This has seen the Thames-Coromandel District Council issue a warning to motorists travelling on the region's roads to watch for flooding and debris.
"Think about what essential supplies you may need if your journey is delayed unexpectedly," the council said.
There are several roads in the Coromandel that have been affected by floods and slips.
Motorists travelling on State Highway 2 Otoko, between Fitzgerald Road and Hihiroroa Road North, are warned about a slip blocking a lane while flooding shut down SH35 between Okitu and Ruatoria in Tairāwhiti at 4pm on Wednesday.
Gisborne's SH35 has been badly impacted by extreme weather events earlier this year and it was more of the same on Wednesday when the road flooded on the Mangatuna side of a new bridge.
Weather warnings
MetService has issued several weather warnings and watches for the eastern areas of the North Island and the northeast of the South Island.
An orange heavy rain warning is in place for the Coromandel Peninsula and Bay of Plenty west of Te Puke until 3pm on Friday.
MetService said the area can expect 160mm of rain at peak rates of 25mm/h, with thunderstorms possible.
Tairawhiti/Gisborne is expected to bear the brunt of the bad weather, with a warning in place until 12pm on Saturday and 350mm of rain anticipated.
MetService warned there could be prolonged periods of rain, which are expected to be heavy at times, with peak rates of 25mm/h and thunderstorms possible.
Heavy rain is also expected to lash the Ruahine Range, Kaweka Forest Park, and Hawke's Bay from State Highway 5 southwards until midnight Saturday.
The area is expected to see prolonged periods of rain, which is expected to be heavy and bring 250mm of rain.
The only warning in place for the South Island is for Eastern Marlborough, south of Ward until 3pm on Saturday.
MetService warned the area could see periods of heavy rain, with up to 250mm expected.
The forecaster warns the areas under the orange warning could see rivers and streams rise rapidly because of heavy rain.
"Surface flooding and slips are also possible and driving conditions may be hazardous," MetService said.
The bad weather comes as Kiwis will experience the shortest day of the year on Thursday.
"Happy winter solstice! Today has the shortest day length of the year. It only gets brighter from here!" NIWA said.
