New Zealanders are being urged to rug up for another chilly night, with MetService warning much of the country is in for another widespread frost before a change in the weather later this week.
Monday morning brought some of the coldest temperatures of the year so far, with overnight temperatures dropping to well below zero across much of the country.
Taupō plunged to -5.6C, Rotorua dropped to -3.9C, Hamilton reached -2.8C and Masterton fell to -4.4C, while Christchurch recorded a low of -4.7C. Lake Pukaki was among the coldest spots, dropping to around -8C.
MetService meteorologist Devlin Lynden said the icy conditions were being driven by clear skies and light winds.
"With calm, clear nights, heat escapes easily into the atmosphere, allowing temperatures to plummet before sunrise,” he explained.
“Sheltered inland valleys become even frostier as cold air settles into low-lying areas.”
Lynden said much of the country was in for another frosty start on Tuesday, with widespread frosts expected across the North Island and inland parts of the South Island.
Fine conditions were forecast from Waikato through to Wellington, including the central North Island, while Nelson, Marlborough, Canterbury and much of Otago were expected to remain mostly fine.
Several showers were possible in Fiordland, Stewart Island and parts of Southland, with isolated showers in Hawke’s Bay and Gisborne expected to clear.
Cold snap boosts electricity demand
Transpower said it had been working with electricity companies to manage periods of "tight supply" this week, as the cold weather increased power use while low wind meant wind farms were generating less electricity.
Transpower executive general manager operations Chantelle Bramley said notices had been issued to the electricity industry to help coordinate the response and ensure enough power was available across the country.
"These notices are part of our standard operating process and the industry has responded to make more generation available," she said.
Bramley said the notices were triggered when the country's backup electricity supply — an extra buffer that could be called on if conditions changed rapidly or equipment failed — fell below, or was forecast to fall below 200 megawatts.
"We are not anticipating any impact on electricity supply to consumers based on current forecast conditions," she said, adding that the system was continuing to operate as intended.
Rain, winds to come later in week
Looking ahead to the rest of the week, the settled weather was expected to continue across much of the North Island on Wednesday, with the possibility of cloud and a few showers developing in the far north and south.
In the South Island, MetService said showers in the west were forecast to turn to rain as conditions changed.
A front was then expected to move onto the country on Thursday, bringing rain to much of the South Island before spreading into parts of the North Island later in the day.
Heavy falls were possible in western parts of the South Island, with MetService warning strong northwesterly winds could also develop.
Behind the front, cooler southwesterlies were expected to bring another drop in temperatures, with snow possible on ski fields and alpine passes.
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