Weather: Atmospheric river to bring heavy rain, muggy temperatures for much of New Zealand

Parts of both islands are already under heavy rain warnings lasting around 24 hours from today, including Coromandel Peninsula from 2pm, Bay of Plenty and Tongariro National Park from this evening Tongariro and Gisborne/Tairāwhiti north of Ruatoria from midnight.

“Streams and rivers may rise rapidly. Surface flooding, slips, and difficult driving conditions possible,” MetService warned.

Severe thunderstorm watches are also in place for Bay of Plenty and Rotorua until 3pm.

Heavy rain is already falling in the South Island’s Westland district, the headwaters of Canterbury lakes and rivers and in northern Fiordland and will continue the rest of today, except in Fiordland. A strong wind watch continues until 9pm in parts of the Canterbury High Country and plains.

Watches are also in place for a wet 24 hours for Waikato, the central North Island and Taranaki from this afternoon and evening.

Tuesday’s emojicast:

         🌧️
           🌧️
             🌧️🌧️
            🌧️🌧️🌧️🌧️
         🌧️🌧️🌧️🌧️
             🌧️🌧️🌧️
                   🌧️☁️
                      ☁️
 
             🌧️☁️
          🌧️☁️
        🌧️☁️☁️                   ☁️
      🌧️☁️
  🌧️🌧️☁️
🌦🌦☁️
   ☁️

— NIWA Weather (@NiwaWeather) November 17, 2025

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.

As well as heavy rain for many, warm nights could also be expected.

“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.”

Much of the country will have enjoyable weather on Sunday.

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

— NIWA Weather (@NiwaWeather) November 15, 2025

MetService forecaster Alec Holden told the Herald a lot of rain was spread across the North Island.

Up to 120mm of rain was expected in Gisborne/Tairāwhiti, 180mm in Coromandel Peninsula and up to 200mm in Bay of Plenty, with localised downpours of 25 to 40 mm/h possible, the largest accumulations likely west of Whakatāne.

Forecasters were most concerned about Bay of Plenty, Holden said.

“There is a moderate chance Bay of Plenty gets upgraded to a red warning in terms of rainfall.”

“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.

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.”

Sign up to The Daily H, a free newsletter curated by our editors and delivered straight to your inbox every weekday.