A "surge of big waves" will be followed by plummeting overnight temperatures next week as we enter the heart of winter.
Cooler southwesterly winds will grip the country on Sunday and Monday, whipping up wave heights and lowering the snow level to 400m over southern New Zealand tonight.
"The cooler southwest winds are affecting places exposed to this wind direction, such as the west coasts of both islands, as well as the southern part of the South Island where a heavy snow watch has been issued," says MetService meteorologist Kyle Lee.
WeatherWatch warns waves of four to six metres will build over the next 24 hours in western areas, before shifting to more eastern areas later on Monday and Tuesday.
"Ferry crossings may have some delays, but nothing too serious looks to be going through the Cook Strait area itself, with the South Island protecting that route for the most part," WeatherWatch says.
The southwest winds ease from Tuesday and give way to a high-pressure system from the Tasman Sea.
The combination of the cooler airmass left over from the southwest winds and the settled weather means overnight temperatures will plummet around mid-week.
"Much of the country is expected to be cold and frosty midweek," Lee says.
"With clear skies, light winds and an already cold airmass in place, minimum temperatures will drop into the negatives for large parts of the country, especially Wednesday morning."
Newshub.
