Demand for electricity rose to a record high this week as Kiwis reached for their heater dials to stave off the cold.

Airports and schools were closed Tuesday as the bitter polar blast battered the country.

Entire towns were cut off when roads were closed, and emergency services were kept busy with weather-related incidents.

Food ran out in some places, sports fixtures were cancelled and black ice and heavy snow made driving treacherous.

Snow fell briefly in Northland, dusting Dargaville, the outskirts of Whangarei and the top of the Tutamoe Range in north Kaipara.

Transpower said the demand for electricity reached a record high, causing stress to the national power grid and “dips” in some areas.

It said the extreme weather led to a peak demand figure of 7048MW at 6pm on Monday – 120MW higher than the previous high, on July 25.

Demand rose a further 50MW about 7.30am Tuesday.

Transpower chief executive Patrick Strange said the grid was being monitored and crews were on standby in case anything went wrong.

“Having snow, ice and lightning across the country for several days is a once-in-a-generation event and I suspect it will keep us busy over the next few days. If we lose power to areas, we’ll do our best to keep it short.”

St John Ambulance was also busy tending to people who injured themselves while walking to work on icy terrain.

– Homepage image / File, Jeanie Griffin

– NZHerald.co.nz, Additional reporting: NZPA