Ahead of it, northwesterly winds are set to make it a blustery start to the weekend for many, Mr Law said.
Aucklanders will wake to a cloudy day on Saturday, with a chance of drizzle for Western areas through the day. By evening a significant front will move in, bringing rain with it overnight.
The rain will clear for a mostly fine day on Sunday.
The South Island will experience the winds swinging back round to the south on Saturday, keeping a few showers around southern and western parts, some heavy and thundery.
The winds will also make it feel cooler, with the return of some colder air to the south of the country.
Early rain and strong winds in Wellington should clear Saturday morning before the Kiwis take on the Kangaroos in the Four Nations Final on Saturday evening at Westpac Stadium.
Although the odd afternoon shower is still possible at the Cake Tin, by kick-off it looks like being a fine evening, with southerly winds and temperatures around 13C.
On Sunday the weather looks settled for most of the country, but a developing system over the Tasman Sea is forecast to head towards the North Island for Monday, bringing the return of some wetter and windier weather for next week.
In the main centres
Whangarei: Tomorrow will be cloudy with rain developing in the evening. The rain will ease by Sunday and the southwesterly will die out. Sat: 22C, 13C. Sun: 21C, 11C.
Auckland: Cloudy morning tomorrow with rain developing in the evening. Rain will clear by Sunday morning, mostly fine. Sat: 19C, 12C. Sun: 18C, 11C.
Hamilton: Rain from tomorrow afternoon and strong westerlies. Fine spells and winds ease on Sunday. Sat: 18C, 10C. Sun: 18C, 7C.
Tauranga: Cloudy with rain tomorrow afternoon and strong westerlies. Fine spells and winds easing on Sunday. Sat: 20C, 11C. Sun: 20C, 12C.
Wellington: Morning rain tomorrow then fine with northerly winds gusting to gale. Few morning showers on Sunday then fine. Sat: 18C, 10C. Sun: 17C, 11C.
Christchurch: Mainly fine, winds turn southwest tomorrow. Chance of early morning shower on Sunday, then mainly fine. Sat: 20C, 5C. Sun: 18C, 4C.
Dunedin: Chance of early rain and showers in the evening tomorrow. Southwest winds dying out on Sunday, mainly fine. Sat: 15C, 6C. Sun: 14C, 8C.