Will it be barbecue or brolly weather this Christmas? That's the question on everyone's lips, and the MetService is predicting not-so-seasonable conditions.

'We've had a very changeable December so far with a cool start, followed by rain and strong winds sinking over the North Island,” says MetService meteorologist John Law, 'while the south basked in sunshine and high temperatures.

Santa might be exchanging his shades for an umbrella this Christmas.

'Although many of us will be getting the chance to have a few days at home and relax over the Christmas period, the weather unfortunately doesn't take a festive break.

'The uncertainties involved in forecasting the weather increase with every step, which means the forecast for tomorrow will be more accurate than one that is made for ten days in the future.”

Higher pressure looks to be the dominant feature, centred out to the east of the country near the Chatham Islands, while a front sits to the southwest of New Zealand.

This set up should leave the country in a more northerly feed of air, resulting in average or slightly above-average temperatures.

In terms of rainfall, showers are possible over the North Island, especially in the north and west and also for the west coast of the South Island, says John.

'There has been some very good agreement in the computer model guidance over the last few model runs,” he says.

'However, as we know in New Zealand, subtle changes in the pattern can cause very different weather.

'Think about the differences we see with the warm northwesterly winds over Christchurch compared to those cooler cloudier conditions when the winds are coming in from the northeast.”

Between now and Christmas Day, the MetService team will be monitoring data from multiple computer models and satellites along with thousands of radar images and observations across the country.

As per usual, the forecast room will be operational 24-hours-a-day right through the Christmas period, says John.