What summer? Wind, rain and thunderstorms on way

Tis the season to be living through changeable Kiwi weather.

A massive storm on it's way to New Zealand, bringing with it widespread heavy rain and gale force winds.

From Monday heavy rain was forecast on the South Island's West Coast, moving to Nelson and Marlborough on Tuesday.

The North Island would get its dose of heavy rain on Tuesday, MetService meteorologist Andy Best said.

"Most places will see rain and possibly heavy falls during the day. And there's the probability of thunderstorms in most areas."

There is still uncertainty regarding the development and track of a complex low over the country next week, but significant weather is expected. For details head to https://t.co/ePtVj8cXwp ^Tahlia pic.twitter.com/t4Jka3O6FP

— MetService (@MetService) December 13, 2019

Severe gales were also possible for eastern South Island areas on Tuesday and into Wednesday.

There was a low risk of severe gale northerlies across almost the entire North Island on Tuesday and the possibility of thunderstorms in most of the North Island the same day.

The weather would begin to ease in the North Island later in the day as the front crossed over the North Island from west to east, Best said.

Temperatures would be average for the time of the year in the North Island - Auckland could expect 22C on Tuesday and 20C on Wednesday - but the South Island would feel the chill of the southerly change on Tuesday.

Highs in Dunedin, Ashburton and Wanaka would be a chilly 16C on Tuesday, about 6C below average.

Showers would start to clear for the South Island on Wednesday, and winds ease, but it would remain cold - Invercargill was expected to only reach 14C and Dunedin 15C.

Summer storm on way, MetService says. File photo / Mark Mitchell

There would be a gradual improvement in the weather everywhere from Wednesday to Thursday, but it would remain cool and damp, Best said.

He urged people to take the storm seriously.

"It is a major weather event and people need to be very much aware and make sure if they're travelling on the roads they drive to the conditions."

The weather, while hardly summery, was not unexpected for the time of year.

"We're in the first month of summer, so we're still in the transition from spring to summer."

Spring was a volatile season and seas were still warming up, and that affected our weather.

"It's the temperature discontinuity between sea and air that causes these active systems."