As we said yesterday the Christmas Day forecast for 2013 is proving a little trickier than previous years due to the spring-like nature of the weather this week and into next. In a nutshell a low will be around New Zealand Dec 24/25 and a high is moving in around 26/27.

The long range data along with our own forecasts is starting to become clearer, and while generally speaking there is a fair bit of high pressure around New Zealand, the possible weak Tasman Low we mentioned earlier this week may well cross the North Island on Christmas Day – bringing an area of rain and showers.

On Monday we said there was a 50% chance of showers in Auckland – today the data has jumped to 80%. However this is what long range models often do so we try and work out the most likely scenario.

Latest rain data today suggests the highest risk areas for rain on Christmas Day will be the western coastline of New Zealand, especially between Westland and Auckland. The rain maps at WeatherWatch.co.nz today suggest this weak Tasman Sea low may bring a period of rain or showers to the North Island especially.  However European models suggest the low will be east of New Zealand by Christmas Day and will bring clearing showers to southern and some esatern areas – while improving conditions spread into the west from an approaching high.

But no matter how you slice it there is one thing that appears to be a common theme – some areas will have hot, perfectly dry, Christmas Day weather and some will have a lot of cloud and some rain.  

At the start of the week we said one of the downfalls of modern longrange forecasting is still trying to lock down the timing of rain. So while we know there will be rain around New Zealand from December 24th to December 26th, we still can’t lock in the exact timing and locations due to this spring pattern we’re in.  So check back for our now daily Christmas Day updates here at WeatherWatch.co.nz.

All long range models we trust point towards this incoming large Tasman Sea high to push in after Dec 25/26 bringing dry, calm and mostly sunny weather to many parts of the country from the 27th to the 29th and possibly beyond.

– Image / Auckland, Zach Knight

– WeatherWatch.co.nz