'Significant front': MetService warns of week-long winter blast with snow, rain and gales

The icy start that left parts of the North Island freezing below -5C is giving way to a prolonged winter blast, with MetService warning heavy snow, torrential rain and gale-force winds are set to sweep across much of the country over the coming week. 

Forecasters say a slow-moving low will bring a multi-day spell of hazardous weather, with more than a metre of snow possible in alpine areas. 

The frosty conditions felt around parts of the country this morning were the final sting of a departing ridge of high pressure, said MetService meteorologist Gerard Bellam. 

Bellam said the ridge had delivered widespread frosts, with temperatures plunging as far north as Auckland before dawn. 

“That was the last remnant of a little ridge of high pressure on its way out,” he said. 

“The coldest part of the morning was around dawn, and it stayed very frosty through to about 8am, when people were out and about.” 

In Hawke’s Bay, the freezing conditions contributed to minor crashes on State Highway 5 between the Summit and Te Haroto. 

Despite the hazards, Bellam said the clear skies brought one silver lining. 

“The bonus after the frosty morning was a beautiful sunny day for people across the eastern North Island.” 

Temperatures dipped well below freezing across many inland areas, with Eastern Rangitaiki on the Napier-Taupō Rd recording -5.3C overnight and Waiouru falling to -4.7C. 

Takapau dropped to -2.8C, while Hastings reached -1.2C, Napier fell to -1.4C, Gisborne touched 0C, and Hamilton recorded -2.8C. 

But Bellam warned the settled weather would be short-lived, with a large, complex low-pressure system now moving on to the South Island. 

“It’s quite a broad low-pressure system with a significant front embedded in it,” he said. 

“We’ve got rain and strong winds with the front, followed by a snow event as a pool of cold air moves in behind it.” 

MetService said the system would unfold over several days, with heavy rain, strong winds and snow affecting different parts of the country as the low-pressure system slowly tracks across New Zealand. 

The first stage is expected to hit on Monday, when a deep and extensive low west of the North Island pushes a cold, moisture-laden southerly flow over the South Island. 

The greatest snowfall is forecast for inland Canterbury and Otago, where snow is expected above about 400m. A heavy snow warning has already been issued for Otago, with significant accumulations expected. 

Rain is also likely across parts of Marlborough and Canterbury, although MetService warned precipitation could turn to snow above about 600m, potentially affecting alpine roads and creating difficult conditions for livestock. 

Strong southeasterly gales are also possible along parts of the West Coast, particularly in Westland and Grey. 

By Tuesday, the slow-moving low is expected to remain near the top of the country, continuing to funnel cold, moist air over the South Island. 

MetService said moderate confidence remained that warning amounts of rain would affect much of Canterbury and eastern Marlborough, while snow could continue falling on higher ground, again affecting roads above 600m. 

The unsettled pattern is forecast to persist into Wednesday as the low gradually moves away to the east. 

Rain is expected to linger across eastern Marlborough and northern Canterbury, while strong, cold southeasterlies could bring severe gales to the Marlborough Sounds and Wellington. 

Snow is also expected to continue affecting higher roads in Canterbury and Marlborough. 

Even by Thursday, MetService said the cold outbreak would not be over. 

Strong southeasterlies are forecast to continue across parts of the country, with a risk of heavy rain extending into Marlborough, Wellington, Wairarapa and Hawke’s Bay. 

Snow could still affect higher roads in Canterbury and Marlborough, while severe southeast gales remain possible around the Marlborough Sounds and Wellington. 

Forecasters urged people, particularly those travelling through alpine areas, to keep up to date with the latest watches and warnings as the prolonged winter blast develops.