Areas about the top of the North Island and the bottom of the South Island will see rain for most of the day until it clears this evening, MetService says.
Central regions will have a mostly dry day with fine weather predicted.
A front moving to the northeast of the North Island brought rain and some heavy showers for areas north of Waikato, MetService meteorologist Sarah Haddon said.
"Northward from Waikato, Taupo and Gisborne, there is occasional rain and showers that will ease as the day goes on.
"The rest of the country is mostly dry, there are isolated showers around some people may see some spitting."
Another cold front was moving up the South Island and was tracking over Southland and Fiordland.
"It will push up to North Canterbury and Hokitika, bringing showers and rain to the southern and eastern areas of the South Island.
"Central New Zealand is nice. It's at the top and bottom of the country where we see this rain."
The weak front tracking north over northern New Zealand this morning would bring a low risk of thunderstorms in Northland and the ranges of the eastern Bay of Plenty.
Looking ahead, a ridge over New Zealand moved to the east on Wednesday and early Thursday, allowing a northwest flow to move northeast over the South Island on Thursday.
"On Thursday, there is low confidence that rainfall accumulations will meet warning criteria in Fiordland and southern Westland.
"In addition, there is low confidence of northwesterly winds rising to severe gale in exposed parts of Fiordland and Southland," MetService said.
On Friday, the front should weaken as it moved on to the North Island, while a ridge of high pressure spreads over the South Island.
The ridge then spreads over central New Zealand on Saturday.
Your weather
Whangārei: Showers, easing in the evening. Light winds. High 18C Low 8C
Auckland: Showers, clearing in the morning and becoming fine. Light winds. High 18C Low 9C
Tauranga: Rain clearing in the morning and becoming fine. Westerlies dying out. High 19C Low 8C
Whanganui: Cloudy periods. A few showers developing this morning then clearing in the afternoon. Light winds. High 17C Low 9C
Napier: Fine. Some evening cloud. Westerly breezes. High 20C Low 7C
Wellington: A few morning showers then fine apart from evening cloud. Northerlies dying out evening. High 16C Low 10C
Christchurch: Cloudy periods and light winds. Showers developing by evening with a southerly change. High 17C Low 6C
Dunedin: Mostly cloudy. Rain from midday with a southerly change, clearing evening. High 14C Low 6C