A fast-moving cold front will bring thunderstorms, squalls and even isolated tornadoes on Tuesday, a forecaster has warned.
"This front has spring written all over it. Warm winds to start with, then a period of either heavy rain or showers, followed by gusty winds and a change to cooler west to southwest winds before midnight," WeatherWatch head weather analyst Philip Duncan said.
This type of weather was normal in spring and many experts believed spring has arrived early this year, he said.
With the front came the risk of thunderstorms, possibly severe.
The large squalls may produce cloud to ground lightning, isolated tornadoes/damaging wind gusts, hail and flash flooding.
"It's not going to last long, it will quickly move in from the Tasman late in the day then clear the country overnight.
For some people in may just be a few showers, for many it will be a short sharp blast, and for a few isolated pockets there could be severe weather," Mr Duncan said.
The risk zone covered most of western New Zealand, particularly the West Coast and from Mt Taranaki northwards.
The MetService warned the western coasts of both islands would also see moderate to heavy southwest swells for the next few days.
Meanwhile, eastern parts of both islands were expected to be largely dry over the next few days, MetService meteorologist Dan Corbett said.
North Island ski fields would benefit from a top-up of fresh snow in the coming days but any real cold air was still remaining well south of the New Zealand for the coming week, he said.