The country has recorded its hottest day of the summer so far - and forecasters are warning the 34.6C reached in Canterbury may only be the beginning, with more sweltering days likely this week.
“It’s going to be hot - straight up,” meteorologist Chris Brandolino told the Herald.
Auckland could reach highs of 27C and 26C until next Monday, while eastern regions of New Zealand could see more temperatures in the low 30s.
RNZ reported that heat alerts have been issued or the lower North Island for Wednesday.
The alerts affect Wellington City, Lower Hutt and Upper Hutt, with the latter expected to be the warmest location, with a maximum temperature of 29 degrees.
MetService issues such alerts when temperatures are set to reach levels that are unusually hot for that location. It is warning of “incredibly warm” and muggy conditions overnight into Wednesday across much of the country.
Auckland should also prepare for a stream of sunny days, with the city’s temperature forecast to remain above 17 degrees for the next 10 days straight.
Brandolino, who is with the National Institute of Water and Atmospheric Research (Niwa), said: “For Cantarbians, for example, the upper 20s is a warm spring day; in Auckland, 27C, 28C, 29C is certainly noteworthy.”
Additionally, humidity in Auckland and elsewhere in the upper North Island could increase closer to the weekend.
“This will see a layer of discomfort. It makes it uncomfortable to sleep. It’s one thing to have a hot, humid day, but when you get consecutive days like this it increases the odds of negative impacts for people susceptible to heat,” Brandolino said.
“People in Auckland will be at a point they may cry mercy.”
Hanmer Forest in North Canterbury hit 34.6C on Monday, he said. This was the hottest temperature recorded this summer so far.
But Thursday, in particular, may be the day temperatures really spike, he said.
MetService has forecast 30C for Blenheim and Timaru for Thursday, while Christchurch was tipped to reach 32C. Masterton and Napier could hit 28C and Twizel could hit 29C. Even Dunedin could hit 28C.
The national forecaster credited some of the hotter temperatures to strong northwesterly winds barrelling in from Australia, creating a “foehn effect”, with hot, dry wind further increasing temperatures, particularly in the South Island on Thursday.
Brandolino said: “You have hot days, but to get to the next level, distinguishable from those pedestrian hot summer days, you need that wind. It mixes the air and that’s when your temperatures really spike.”
In the meantime, winds from the east would see hotter temperatures in the centre of the North Island, such as Manawatū and Waikato - “these areas could flirt with the 30s, certainly the upper 20s,” Brandolino said.
Some factors behind the warm temperatures included above-average ocean temperatures around New Zealand, the “import” of hot air from Australia and a “mechanical mixing” of air when it drops in elevation after passing over the Southern Alps.
MetService meteorologist Ngaire Wotherspoon highlighted the fire risk around the South Island.
“These dry conditions and high temperatures can be accompanied by increased fire risk, so be sure to check the risk for your area on the MetService website and checkitsalright.nz before lighting any fires,” she said.
Raphael Franks is an Auckland-based reporter who covers breaking news. He joined the Herald as a Te Rito cadet in 2022
Landscape architect Brittany Smith took out the senior title.