Soaring temperatures and gusty winds have firefighters across the top of the South Island on full alert today.
A forecast mini heatwave could see temperatures up to 35degC and a total fire ban across Marlborough will take effect at 8am today.
Principal rural fire officer Richard McNamara says there's an extremely high risk of a massive bush fire and people need to be sensible.
"That total fire ban extends from the Wairau River to the Conway River which includes all of central Marlborough and down towards the Canterbury border," he says.
Temperatures could hit 35degC today and tomorrow.
The heat will be putting extra strain on the already stretched fire service which has already dealt with two large forest fires in Marlborough in the past few weeks.
Meanwhile, warm air from Australia is sweeping across the country, with temperatures in Dunedin hitting 27.2degC this morning.
Gore has experienced an excessively warm night with temperatures of about 21.6degC to 22.6degC, MetService meteorologist Philippa Murdoch says.
It may be a record for the Southland town where the average December overnight temperature is 8.3degC, she told NZ Newswire.
"It's very sultry."
Temperatures are expected to be in the 30s from Dunedin to Picton and may break records on the South Island east coast.
It is forecast to hit 35degC in Blenheim which will surpass the previous best for December of 33.2degC in 1948.
Temperatures in the North Island are expected to be in the 20s.
On the downside, the heatwave with warm northwesterlies is increasing the fire risk in the east and the Fire Service is urging caution.
Rain and lower temperatures are forecast tomorrow, but conditions are expected to improve for Christmas Day with mainly fine weather across most of the country.
RadioLIVE / NZN