"The front is expected to bring periods of heavy rain across the upper North Island and this watch covers the possibility of rainfall accumulations approaching warning criteria in Northland and Auckland from Friday afternoon through to Saturday morning," MetService said.
A heavy rain watch was in place for Northland from 3pm this afternoon to 6am Saturday as well as a warning for Auckland and Great Barrier Island from 11pm tonight to 11am Saturday.
A strong wind watch was also in place for Auckland overnight with winds expected to gust up to 100km/h.
"Daytime heating and wind convergences" were expected to bring showers in many regions through Friday afternoon and evening.
There was a low risk of thunderstorms for the North Island in the afternoon and evening from Taranaki to Kāpiti, including Taumarunui, Taihape, Taupō and the eastern ranges of Bay of Plenty.
The risk was considered moderate around inland areas of South Taranaki and Whanganui, and about Taihape and the eastern ranges of Taupō and the Bay of Plenty.
For the South Island, there was a low risk of thunderstorms from northwest Nelson to Westland over Fiordland, Southland and Otago.
The risk was moderate around Southern parts of the Southern lakes, the Fiordland lakes and Southland.
Looking ahead to next week, rain would ease to showers over most of the country and the low over the Tasman Sea weakened and moved southeast over the country.
"Showers may be heavy with isolated thunderstorms. On Tuesday, another front moves east on to the South Island, with further showers about the North Island.
"Periods of rain affect western parts of the South Island from Monday to Tuesday, with the heaviest falls about the Westland Ranges."
Your weather
Whangārei: Occasional rain, possibly heavy this evening. Northeasterlies gradually picking up. High 21C Low 16C
Auckland: Cloudy with a few showers, then rain from evening. Northeasterlies gradually strengthening, possibly gale evening. High 21C Low 16C
Tauranga: Cloudy with a few showers. Southeast turning northeast morning, then strengthening. High 21C Low 16C
Whanganui: High cloud increasing. A few afternoon and early evening showers. Light winds. High 24C Low 14C
Napier: Mostly cloudy with occasional showers. Northeasterlies slowly picking up.
High 20C Low 16C
Christchurch: Occasional drizzle, especially morning and night. Northeasterlies freshening afternoon. High 18C Low 13C
Dunedin: Fine spells, but occasional drizzle. Fresh northeasterlies. High 17C Low 13C