Updated Friday — Christmas Day looks fairly calm but will be cooler in the south & east and both islands have a risk of showers.
RAIN / SHOWERS:
No widespread rain is forecast for Christmas Day over NZ. At this stage it looks more like showers will form in both the upper/central North Island and the lower/eastern South Island. Although showers may form anywhere over NZ these are the highest risk areas.
It looks as though the North Island showers will expand with daytime heating. They may drift into parts of Waikato, Coromandel Peninsula and Bay of Plenty.
South Island showers look lighter with a cooler airflow, although again inland during the day we may see some heavier downpours. Check your local 10 day forecast for where you will be on Christmas Day. If rain/showers are showing up hopefully this update and the maps below provide some context. Please note, once these showers have formed light winds or sea breezes may guide them into new areas, which is why some forecasts show a low chance of showers in surrounding areas.
Christmas Day will be cooler for some in the lower South Island and along the eastern coastline. The good news is that in recent days the forecast temperatures have crept up a degree or two but Southland and Otago look coolest, especially coastal Otago. There’s a good chance Southland, with high pressure growing right nearby, will become warmer in the afternoon especially if the sun gets out. Showers will be expanding around the lower/eastern South Island which will cap daytime highs. Here are the coolest main centres with highs between 11 and 15 degrees at this stage.
In the North Island some places look to be cooler than normal, at this stage southern and eastern areas look to have highs in the late teens, in places like:
Slight changes in windflows may alter the above temperatures by a couple of degrees.
Warmest areas look to be in the very north of NZ and areas leaning west. The West Coast, after all the rain recently, looks dry on Christmas Day.
WHAT THE MODELS ARE SAYING FOR 12 NOON DECEMBER 25:
ECMWF – Pale blue indicates only a low risk of a shower, darker blue indicates where showers are most likely to develop/grow.
GFS – A more simplistic lower res version of the map above helps pinpoint the highest risk areas for showers.