Christmas Day weather: 'It's a patchy affair'

Most of the country is in for unsettled, cooler weather this Christmas Day as a wet front makes its way up the country.

MetService forecaster Ian Gall said tomorrow would be generally fine for most places, although the wind would pick up in Wellington.

A trough moving in from the Tasman sea would start to produce rain in the deep south late tomorrow, which would move up the West Coast on Tuesday and bring heavy showers with it.

The front was expected to be sitting near the middle of the country by midnight Tuesday before sweeping over the North Island on Christmas Day.

"It's quite a patchy affair. It's just going to be quite an unsettled day with most people seeing some rain at some stage,'' Mr Gall said.

"But at least the front moves through pretty quickly over the North Island on Christmas Day ... and some places will get fine spells.''

Accompanying the rain, south-westerly winds would bring cooler temperatures for most of the country, which has so far enjoyed a warm December.

"It won't be cold but there will be a noticeable cooling when the front goes past,'' Mr Gall said.

"The winds will be changing pretty readily on Tuesday over the South Island to the cooler southwesterlies and it'll happen over the North Island on Christmas Day.''