Christmas lunch looks like being an indoor affair for much of the country

It's already raining in parts of the North Island...Rotorua and northern Hawke's Bay have had showers.

WeatherWatch's Philip Duncan says the rain could get heavier - and hit Bay of Plenty, Waikato and the Central Plateau.

And parts of the South Island are also in for it.

He says a cool easterly is coming into Canterbury and some parts of Otago - bringing some heavy downpours.