It's a wet Christmas: soggy forecast for upper North Island, South Island place to be

If you're planning on a beach day in Auckland on Christmas you might need to pack an umbrella. Photo / File

It might be more a board games than barbecue kind of Christmas for the upper North Island with a sub-tropical storm set to spoil the fun.

For Northland, Auckland, the Coromandel Peninsula and parts of Bay of Plenty the forecast, at this stage, was for rain, heavy falls and strong northeasterly winds.

Severe weather watches and warnings were a possibility.

MetService meteorologist Lisa Murray said she was sorry to bring the "unfortunate news".

"A broad rain band will be moving south over the North Island, so basically anything north of Taranaki, Taupō, the central North Island, will see rain on Christmas Day.

"It might be a good idea to get the board games out on Christmas and save the barbecue for a few days later."

Santa is set to ride a river of moisture into New Zealand this Christmas, especially for the North Island 🎅 🛷 💧

The best weather looks to be across the lower South Island. pic.twitter.com/plrdI3A30z

— NIWA Weather (@NiwaWeather) December 19, 2018

Murray said the forecast was still a little uncertain given how far away Christmas was, so it was important anybody travelling in those areas stayed up to date with the forecast and any weather watches or warnings.

"MetService is the official forecaster, and if anything major happens we liaise with Civil Defence and regional councils. If you are thinking of travelling Christmas or Boxing Day in those areas make sure you check the forecast."

The lower North Island would escape most of the wet weather, Murray said.

"Wellington is not looking too bad. People should be able to get the barbecue completed and their outdoor activities done before some cloud arrives in the afternoon and some showers by the evening."

The South Island would be the place to be though, sitting under a ridge of high pressure keeping things nice and settled.

Nelson would be the pick of the bunch, with a high of 24C and light winds.

Christchurch would see similar temperatures with slightly stronger northeast sea breezes, while Dunedin was also in for a fine Christmas.

WeatherWatch NZ analyst Philip Duncan was also forecasting a potentially wet Christmas in the Upper North Island, and mostly dry weather in the lower half.

Duncan said the South Island was in for a mostly dry, sunny day with light winds.

"A chance of late clouds in Nelson and Marlborough and potentially even some drizzle later in the day in the north should the North Island low come further down the country."

Daytime highs were forecast to be 23C to 26C across the country.

Murray said a low pressure system was coming through on Saturday, moving quite quickly, but bringing rain to most eastern facing areas in the North Island.

This would move down to the South Island by Sunday.

In the upper North Island conditions would improve by Sunday evening before another low deepens to the northwest of New Zealand on Christmas Eve, moving on to the upper North Island on Christmas Day.

The good news was several days after Christmas the weather was looking much better across the country.

"Once that low moves away later in the week a ridge of high pressure should move in bringing plenty of sunshine," Murray said.