Weatherwatch.co.nz said the six lows set to cross New Zealand in the coming week and a half would unleash wet and wintry weather over both islands.
The forecaster said although not all lows were stormy, at least three were expected to produce "severe weather risks".
Next week the top of the country was at risk of thunderstorms and pockets of heavy rain from warm sub-tropical air colliding with cooler air in the south.
This winter pattern was the most unsettled the North Island had seen in half a decade, following five years of general rain shortage across the top half of the island, said the forecaster.
MetService said the first burst of rain for northern and central regions was due to soak northern and western regions today, marking the start of days of rain heading into the school holidays.
"The trough is expected to move northwards on Wednesday, with rain retreating to the Far North.
"However, the reprieve from the wet weather over northern and central New Zealand is expected to be short-lived, as the trough sinks southwards on Thursday, bringing with it further rain and the potential for heavy falls," posted the forecaster on Facebook.
Weatherwatch.co.nz said at the same time a spell of mid-winter weather was on the way for the bottom of the country with very cold air ushering in freezing nights. Snow was also in the mix this weekend.