Mild but unsettled weather ahead

Photo / Greg Bowker

A mild but unsettled week is on the cards as spring-like conditions set in early - but winter could make a comeback by the weekend.

WeatherWatch head analyst Philip Duncan said the weather would be a "chopping and changing" all week.

Sun, showers and clouds were forecast for the country, with rain expected particularly for the south and west of the South Island.

A storm brewing in the Southern Ocean would be "parked" below New Zealand for the week, bringing northwesterly winds across the country while parts of Australia were plagued by wintry southerlies.

This would flip by the end of the week, Mr Duncan said.

"It's quite a different forecast from one side of the Tasman to the other but it will stay all week.

"We think ... spring has arrived early this year. Spring doesn't mean an end to wintry weather, spring's a mixture of winter and summer basically.

"That means changeable. It'll be chopping and changing all week long."

The low bringing the northwesterlies would move further south on Friday, with colder southerlies moving in to the South Island by Saturday and the North Island on Sunday.

Temperatures would drop with the icy blast, compared with the almost balmy start to the week, Mr Duncan said.

"We're back to winter again by this weekend and it'll feel like winter. It'll be very cold. It's a polar change coming through," he said.

MetService meteorologist Emma Blades said a series of fronts moving up the country would bring rain to a lot of the country this week.

Temperatures should be fairly mild across the country in the first half of the week -- with Christchurch possibly reaching 20C on Monday.

A severe weather warning is in place, with heavy rain expected in the Westland ranges as well as Buller and Canterbury throughout Monday and into Tuesday.

There was a moderate risk of thunderstorms with the heavy rain, MetService said.

Snow flurries in the south and plummeting temperatures would come with the icy blast form the Antarctic by the weekend, Ms Blades said.

Meteorologists are also reporting signs of an El Nino weather pattern, which is partly to blame for the southerly outbreaks over winter.

In New Zealand, the system typically brings higher rainfall to regions that are normally wet and often drought to areas that are usually dry.

Monday's forecast:

• Whangarei: Cloudy at times. High 20C
• Auckland: Cloudy periods, few showers. High 17C
• Hamilton: Cloudy with light rain at times. High 17C
• Wellington: Cloudy with occasional rain. Gusty winds. High 14C
• Christchurch: High cloud. High 19C
• Dunedin: High cloud, clearing in the afternoon. High 14C
• Queenstown: Rain at first, fine afternoon. High 13C

Tuesday's forecast:

• Whangarei: A few showers, evening rain. High 18C
• Auckland: Scattered showers, evening rain. High 17C
• Hamilton: Drizzle to rain, chance of heavy rain later. High 16C
• Wellington: Rain, chance heavy, easing. High 14C
• Christchurch: Mainly fine, possible evening showers. High 17C
• Dunedin: High cloud, spots of rain. High 12C
• Queenstown: High cloud, spots of rain. High 10C
Source: MetService