As the front moved northeast through the day there would be a moderate risk of thunderstorms this afternoon and evening in the far east of the Bay of Plenty and the far north of Gisborne.
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The front would be followed by a cold, unstable air mass spreading north over the country, and a risk of thunderstorms across much of the South Island.
A southerly change would bring a moderate risk of thunderstorms in Wellington, Kapiti and the south of Wairarapa late this afternoon and this evening.
There will be some respite over the weekend, though, with just a few showers scattered around the country Saturday, and Sunday looking like the best day for outside activities for most of the country.
"Sunday is looking very good for the North Island in particular, with fine conditions for everyone and just the odd bit of cloud and a shower possible."
James said with the fine conditions enticing people into the water, those on the west coasts of both main islands needed to be extra careful as a large swell swept up the country.
"This is quite a significant swell, and [for a] long period so [be] extra powerful."
The rough conditions should persist from Sunday evening, peaking Monday and last through to Tuesday, James said.
Another, weaker front would sweep over from the southwest on Monday, meeting a warm low from the north just east of the country on Tuesday, Christmas Eve.
The low from the east would bringing some showery conditions to the East Coast for Christmas Day.
"Normally, with the fronts approaching from the west, it is the east that gets the fine weather. But, instead, it is looking like the fine weather spots like Gisborne, Napier and Christchurch will have some showers, while western areas are looking pretty good."
