Santa could find himself fighting gale force winds in some areas tonight before rain heralds in Christmas Day for much of the country.
MetService says while Christmas won't be a complete washout, holidaymakers can expect some showers to put an initial dampener on beach plans.
A front moving up the South Island today is predicted to hit Wellington late this afternoon, bringing gale force winds, before moving up to Auckland by Christmas morning, said MetService meteorologist Dan Corbett.
The weather should improve in most northern areas by tomorrow afternoon.
However the South Island would experience another "fly in the ointment'' tomorrow as a low is due to bring showers to Dunedin and Christchurch after a dry start to the day, Mr Corbett said.
Those travelling to holiday spots or to visit family around the North Island might want to make back-up plans if heading to the beach for Christmas.
The Coromandel was set to see rain tonight and a damp start to Christmas Day, improving in the afternoon, while Boxing Day brought a risk of the odd shower.
Hawke's Bay could get "a few spots of rain'' tomorrow morning but a westerly wind would bring dry weather.
Temperatures there were "quite respectable'' - in the mid-20s.
Whangarei would be slightly warmer than Auckland tomorrow, but the rain will take longer to clear in the morning, while Boxing Day would be "pretty good''.
Taranaki will get showers later this evening, with north westerly winds and a few showers thinning out through the day tomorrow.
A few showers will also come through on Boxing Day, easing by the end of the day.
* Auckland: Rain tonight easing to showers mid-morning before a southwest change and a high of 22C. Showers continue through Boxing Day, becoming more frequent in the evening with a high of 21.
* Hamilton: Cloudy with northwesterly breezes today, leading into rain tonight. Christmas morning brings a few showers before a southwest change and a high of 21C. Boxing Day brings showers in the afternoon with a high of 21C.
* Wellington: Rain and gale force northwest winds up to 110km/h tonight will ease slightly tomorrow, with fine spells and a high of 22C.
Showers and a fresh northerly continue throughout Boxing Day with a high of 18C.
* Christchurch: High cloud tonight breaks for a fine Christmas morning before showers and southwesterlies develop late morning, with a high of 22C.
Boxing Day remains cloudy with rain easing and a high of 17C.
* Dunedin: Occasional showers tonight which will continue throughout tomorrow with a high of 17C. Morning rain will ease on Boxing Day and southerly winds will turn easterly with a high of 16C.