The storm in space has been upgraded from severe to extreme, the highest category scientists use to measure these sorts of galactic weather events.  

Transpower has issued a “grid emergency” notice in New Zealand and is removing some transmission lines from operation due to the onset of the geomagnetic storm.  

A spokesperson for the agency, which operates the New Zealand power grid, said the storm is likely to affect Earth over this weekend because of significant solar activity.  

The space weather event was upgraded from a G4 geomagnetic storm to a G5.  

“As part of our contingency plan we are removing some transmission lines from service across the South Island as a precaution. In order to do this, we have to issue a grid emergency notice, however, this initial action should not impact supply of electricity to consumers.”  

The notice was initially due to last until noon but it has now been extended until 6pm.  

At this stage, the spokesperson said they do not anticipate any impact on New Zealand’s electricity supply to consumers.  

AP reported the storm could produce northern lights in the US and potentially disrupt communications over the weekend. An extreme geomagnetic storm in 2003 took out power in Sweden and damaged power transformers in South Africa, the agency said.  

A US National Oceanic and Atmospheric Administration forecaster said these storms, ranked on a scale of 1 to 5, posed a risk for high-voltage transmission lines for power grids, not the electrical lines ordinarily found in people’s homes.  

Meanwhile, back on Earth MetService have said nights will remain cold well into next week, and while it has forecast cloudy skies around the country this weekend, Auckland should enjoy fine, clear conditions.  

It comes as New Zealand grapples with a cold snap, having seen a run of chilly days and a threat that high electricity demand could outstrip supply and necessitate power cuts yesterday morning.  

The National Institute of Water and Atmospheric Research (Niwa) said the coldest temperature was recorded at Cass, Canterbury, where it fell to -9.7C. MetService said Christchurch hit -6.3C, Masterton fell to -3.5C and Palmerston North dropped to -3.1C.  

Transpower issued a warning notice a day earlier and people were asked to conserve electricity by turning down their heaters, not charging their electronic devices or vehicles, and delaying any washing or drying. 

The efforts people made to limit their power usage, along with reductions from industrial users and extra electricity generation, meant the country avoided a major grid emergency and power cuts never eventuated, Transpower said.

Even though the cold temperatures will remain, Transpower chief executive Alison Andrew said there was no reason to expect any further need to conserve electricity over the weekend.

“Thank you to all New Zealanders who acted to reduce their electricity demand this morning. It made a difference, and we appreciate it,” Andrew said.

Auckland in for sunny Sat, 15C: Forecasts around NZ 

MetService has forecast a fine Saturday and Sunday for Auckland. Today, the temperature was tipped to reach 15C and 16C tomorrow. 

Cloudy mornings were expected for next week, with rain setting in from Wednesday. 

In Wellington, MetService forecasts a mostly cloudy Saturday with occasional showers. It should clear to fine in the afternoon and the temperature should reach 12C. Sunday should reach 12C and the day should remain partly cloudy. 

Christchurch had a mostly cloudy forecast for Saturday. Some showers were possible, mostly confined to the Banks Peninsula and clearing by midday, MetService said. It should reach 12C and on Sunday, with fine conditions, temperatures should rise to 14C. 

Snow in Porters Pass this week. Photo / George Heard 

Saturday would see cloudy periods in Dunedin with a temperature high of 11C. Sunday would turn cloudy in the afternoon, MetService said. It should reach 14C. 

MetService meteorologist Mmathapelo Makgabutlane said this May provided a stark contrast to last year, being a lot colder. 

“Many may recall the tropical-feeling temperatures of May 2023, where places like Auckland and Hamilton experienced record-breaking warm nights. However, this year, expect an overnight drop to mid-single digits in Auckland City and early morning temperatures hovering near freezing in Hamilton,” she said. 

Raphael Franks is an Auckland-based reporter who covers breaking news. He joined the Herald as a Te Rito cadet in 2022.