Christmas Day weather could be a cracker according to a long-range computer model at WeatherWatch, but rival MetService says it's far too early to make an accurate prediction.

Long-range models of the weather leading up to Christmas were pointing towards a large high moving over the Tasman Sea in the week leading up to the 25th, WeatherWatch said.

However, it also warned the tropics would also be very active, mainly to the northeast.

The Southern Ocean continued to pump weak fronts into the Tasman Sea bringing a fair bit of cloud to the west and the odd shower.


The high, moving in before Christmas, looked likely to be dominant but the long-range models still weren't sure about where the high will be placed for Christmas Day, or if a potential tropical low could impact it.

WeatherWatch head analyst Philip Duncan said a lot of dry weather would be coming in over the next couple of weeks, however there could be a few wet patches in the mix.

"Southern Ocean storms have been clipping southern New Zealand while the odd tropical system has been clipping the north. This pattern looks to continue for a few more weeks.''

A wet sub-tropical low was 30 per cent possible, however current data suggested the high would win out.

MetService meteorologist Tuporo Marsters said it was too early to make a call on Christmas Day weather.

Forecasters could only look 10 days ahead, but that would still be ``a bit vague'', and only a week ahead could be comfortably predicted.

By mid-next week, forecasters should have some idea whether it would be wet or dry on the day, Mr Marsters said.

"But at this stage, no, it's too far ahead for us to make a guess. Even our model data doesn't go that far, I'm afraid.''