A wet and windy Monday will be the prequel to a wintry week of gales and heavy rain predicted in the Waikato and snow on Mt Ruapehu skifields.
Trampers were advised that rivers and streams could rise rapidly and slips were possible in vulnerable areas, MetService said.
The front was forecast to move across New Zealand throughout the day and be preceded by a strong to gale northerly wind.
Heavy rain hit Hamilton yesterday, beginning mid-morning, and was expected later in Auckland, Northland and Tauranga.
A severe weather watch was in place yesterday for Bay of Plenty and heavy rain was expected to fall about the eastern Bay of Plenty Ranges from yesterday afternoon until early this morning.
MetService said a polar blast was expected to move up the country tomorrow, bringing showers to eastern areas and snow to low levels.
Skifield operators are salivating over the forecast - which has predicted the first big dumping of snow for the season.
Heavy snow was expected to fall from tomorrow to Friday, down to 700m on the Central Plateau around Mt Ruapehu.
A warmer than normal winter so far had made for small snow bases and delayed the opening of Whakapapa and Turoa skifields - which should have been June 28.
Annah Dowsett, customer relations manager for Mt Ruapehu, said she could not yet estimate when the skifields would open, but the situation would be assessed day by day.
"As the snow falls we will try and get facilities operational. We're really optimistic that it will deliver a good amount of snow."
Judging by the forecast, Dowsett said National Park, at 825m, should receive a decent coating, and Waiouru would see some powder.
"We're stoked on the forecast and we're waiting with bated breath."
Lisa Splitt, retail assistant at board and ski hire shop Ski Biz at National Park, said she hoped the announcement would kick life into the dormant season.
"Everyone's happy - we're just hoping it will be a lot of snow. People haven't really been coming in because it's been delayed so we're getting ready for the snow now."
She said retailers were hopeful the skifields would open this Saturday.