It's bone-chillingly frosty in the South Island while temperatures inch closer to summer levels in the North Island this afternoon.

A high-pressure system in the South Island has locked in the overnight cold, as cloud cover blocks out the sun's rays from warming up chilly Southlanders and a number of places sitting below zero degrees this afternoon.

And Weatherwatch warns it will get much colder this evening, with temperatures expected to dip as low as -5C in some parts of the South Island.

The cold snap comes courtesy of a "smiley face" high pressure system around the South Island, the weather forecaster said.

Advertisement
The
The "smiley face" high pressure system around the South Island. Photo / Weatherwatch

One of several high-pressure systems that have taken this shape around the South Island in previous months, it ushers in clear skies overnight inland and throughout the highlands, with sub-zero temperatures expected in some regions.

But in a contrast rarely seen in New Zealand, the North Island will see above-normal temperatures recorded for this time of year, as Southlanders shiver.

Subtropical winds from as far away as Tonga, the Cook Islands and New Caledonia streaming over the North Island means some areas will not drop below 14C tonight.

But Northlanders are set for their own share of forecasted dramas, with six weather warnings active north of Napier from this afternoon until Friday evening.

Gisbourne is set for a hammering of rain tomorrow, with periods of heavy rain - potentially approaching warning criteria - on the cards and a heavy rain watch in force from 3am-9pm Friday.

North of Tolana Bay and around the ranges will be drenched with up to 150mm of rain, with a heavy rain warning set from 6pm tonight for 24 hours.

Peak rainfall of up to 20mm/h is expected on Friday morning and early afternoon, with surface flooding and slips possible and driving conditions compromised.

Locals have been warned that the heavy rain may cause rivers and streams to rise.

Advertisement

The Bay of Plenty area west of Te Puke, including Tauranga, is set for a drenching, with periods of heavy rain that may approach warning criteria.

Meanwhile Western parts of the Coromandel Peninsula and the Waikato area near the Kaimai range will see easterly winds that may approach severe gale at times.

A dousing is also expected in the Coromandel Peninsula, with a further 100-140mm expected to hammer the area on top of what has already fallen.

With a heavy rain watch in force for the area, Metservice warns that peak rainfall rates of up to 25mm/h will fall, with localised downpours of up to 35mm/h possible this afternoon and evening, especially in the north.

Slips and flooding have forced the closure of four sections of the State Highway in the area today, with three remaining closed this afternoon.

Motorists are advised to drive to the conditions and check NZTA's traffic map for details.

Advertisement

The warning is in place for the Coromandel Peninsula until 9pm tonight, with motorists warned to watch out for hazardous driving conditions, surface flooding and slips.

Live temperatures updates from Weatherwatch's weather stations can be found on its website.