Two weather systems will converge to drag an atmospheric river down to New Zealand, bringing heavy rain and warm nights.
Earth Sciences New Zealand (formerly Niwa) forecaster Chester Lampkin told the Herald an area of low pressure in the Tasman Sea and a cold front coming in from the southwest would bring a big plume of moisture from the Tasman.
Much of the country will have enjoyable weather on Sunday.
— NIWA Weather (@NiwaWeather) November 15, 2025
Looking to Monday/beyond: Air flows will favour the NW-NE, importing warmth & moisture (consistent with La Niña).
Heavy rain is a good bet over parts of NZ next week. Best to stay on top of the forecast with @MetService pic.twitter.com/rjyHRNMuqi
“We call it an atmospheric river because the amount of moisture coming with it,” he said.
“There is an area of high pressure to the east that is blocking the weather pattern, where it slows the weather down to almost a standstill which makes the storms move a little bit slower.”
MetService forecaster Alec Holden told the Herald a lot of rain was spread across the North Island.
MetService has issued a series of heavy rain watches and warnings across the centre of the North Island from this afternoon and evening until tomorrow afternoon.
🟠 Severe weather update, Monday 17 Nov 🟠
— MetService NZ (@MetService) November 16, 2025
Heavy Rain Warnings start from Monday night in the South Island, and Tuesday afternoon in the north.
A strong wind watch is also in place for Fiordland and western Southland.@nztacwc @nztaos @nztawbop pic.twitter.com/JfRIE3c0r7
A heavy rain warning will come into force for the Coromandel Peninsula from 2pm until 11am tomorrow, with 140-160mm of rain forecast.
A heavy rain warning is also set to begin for the Bay of Plenty from 8pm until 5pm tomorrow.
“Expect 150 to 200mm of rain with intensities of 20 to 25mm per hour possible,” MetService said.
The Bay of Plenty was the area for which forecasters were the most concerned, Holden said.
“There is a moderate chance Bay of Plenty gets upgraded to a red warning in terms of rainfall.”
Holden said the rain across the North Island would likely be widespread.
🌧️Rain is heading the North Island's way Tuesday🌧️
— MetService NZ (@MetService) November 17, 2025
While rainfall isn't forecast to reach warning amounts over the whole region, some spots in Northland and Auckland could see heavy falls, so stay weather aware tomorrow.@AklCouncil @AucklandCDEM @nztaaklnth pic.twitter.com/XKNw0ukwly
“Over the next couple of days, I would be shocked if anywhere on the North Island managed to skip out on some amount of rain.”
In the South Island, multiple heavy rain warnings are currently in place for the south and west of the island, which are set to expire this afternoon.
Between 120-150mm of rain has been forecast to fall across the headwaters of the Canterbury Lakes and Rivers, Fiordland north of Doubtful Sound and the headwaters of Otago Lakes and Rivers.
However, between 150-200mm of rain is forecast to fall across the Westland District until 8pm.
Holden said the rain was currently confined to the higher areas across those affected regions.
“A lot of it is over the spine of the South Island, across the main divide,” he said.
MetService has also predicted the air mass would bring warm temperatures alongside the rain.
Holden said while most daytime temperatures would linger in the early to mid-20s, the night-time temperatures would only be a few degrees colder.
“Auckland is staring down the barrel of an 18C minimum, while places like Rotorua can expect minimums of 16C or 18C,” he said.
“Which I imagine for them will be significantly more unpleasant because they don’t get it as much as Auckland.”
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