Much of the country is in for a battering as two significant storms bring heavy rain, strong winds and possible thunderstorms.
The first storm is tracking north to south down the Tasman Sea. It isn't expected to make landfall in New Zealand but will hit very close to Fiordland on Monday night.
WeatherWatch said it will bring the risk of severe weather and will almost become a "weather bomb".
"Storm 1 is currently rapidly deepening in the north Tasman Sea and will be very close to reaching weather bomb criteria, with the central air pressure dropping over 20hPa in the 24 hours from noon Sunday to noon Monday," the forecaster said.
The worst of the storm looks like it will hit mostly at sea but strong winds gusting to gales and heavy rain is expected in the north and west.
WeatherWatch said the wild weather will hit both islands and generate dangerous beach conditions for the west of the country.
The second storm is tracking west to east and is moving in hot on the heels of storm one. The low-pressure zone is so close to the first storm, WeatherWatch said it will get stuck in its orbit and create a new "really big and very deep low-pressure zone in the south Tasman Sea" by mid next week.
"On Wednesday morning, it is currently forecast to have air pressure near Fiordland of just 959hPa - incredibly rare to see low pressure that deep near NZ and is more akin to a major Southern Ocean storm down near Antarctica - or that of a tropical cyclone to our north," WeatherWatch said.
The second storm is also likely to have a significant impact on the country because it's tracking sideways across Aotearoa.
"Storm two will peak early on Wednesday morning - then as it moves into NZ it will weaken slowly, but will take until the weekend to clear off," the forecaster said.
MetService has issued several warnings relating to the first storm for the upper North Island.
Northland, Auckland, Great Barrier Island and the Coromandel are all under heavy rain watches. The regions can expect heavy rain and possible thunderstorms until Monday evening.
Strong wind watches are also in place for the areas, excluding Coromandel, with severe gales forecast for exposed areas.
Gisborne, the Bay of Plenty and Rotorua are also under heavy rain watches with thunderstorms possible for Gisborne and BOP.
Down south, Motueka is under a heavy rain watch with periods of heavy rainfall expected into Monday.
WeatherWatch said it expects the forecaster will issue warnings for storm two as well
