Heavy rain watches were also issued for Northland, Auckland from Whangaparāoa north, Great Barrier Island and the Coromandel Peninsula - the earliest of which begins at 6pm today.
Peak rainfall rates during the electrical storms could reach 40mm an hour, MetService said.
Forecasts would be monitoring the thunderstorms closely, and a red thunderstorm warning will be issued if any severe storms are detected on their radars.
A low-pressure system is responsible for driving the sunny, frosty days away with the front due to reach the North Island this evening.
Private forecaster WeatherWatch said sub-tropical winds should lift the temperatures in most regions over the next week.
MetService meteorologist Ngaire Wotherspoon said: “Northland is likely in the firing line starting this evening, until at least late tomorrow morning as the front tracks south.
“We expect the front to reach Auckland early Friday morning when a heavy rain watch comes into effect from Whangaparāoa northwards.”
By Friday afternoon, the heavy rain is likely to spread to Coromandel with the low-pressure system travelling east across the island.
Wotherspoon said there was still some uncertainty about where the weather would be the most violent.
She said showers would linger around the north of the country into the weekend, while heavy downpours move over Gisborne, Hawke’s Bay and Wairarapa.
The National Institute of Water and Atmospheric Research said the low-pressure would become more common over the next two weeks, with westerly winds becoming more common later this month.
Raphael Franks is an Auckland-based reporter who covers breaking news. He joined the Herald as a Te Rito cadet in 2022.
