Auckland could expect a "very nice" Saturday, with temperatures in the mid-20s for the one-day cricket international between New Zealand and India at Eden Park.
"There might be a bit more cloud in the evening by Saturday and then by the time we go into Sunday, we'll already start to see maybe a few spots of rain in the morning," Mr Corbett said. "But certainly by the afternoon, that's when we bring in some wet weather from a passing front."
Showers would clear on Monday morning in time for the Anniversary Day regatta and Laneway Festival.
"It's not a washout, it's just early on it might be damp. It's an improving picture I'd say for the day," Mr Corbett said.
Weather Watch head weather analyst Philip Duncan said a small but aggressive low pressure system was expected to hit the South Island on Sunday.
"That's going to drive in some strong to galeforce winds, some heavy rain across big parts of the South Island and lower North Island.
"One bit of silver lining is that the worst weather will be furthest away from the regions that are on holiday."
The low would be followed by a high pressure system expected to roll into the country next week, bringing better weather for most regions.
"We think January will end fairly settled and warm for most parts of the country," Mr Duncan said.
Weekend weather round-up
* Auckland: Fine tomorrow with a high of 25C, rain on Sunday, drying as Monday holiday progresses.
* Hamilton: Fine tomorrow with a high of 25C, cloudy and wet early on Sunday.
* Wellington: Dry but windy with a high of 19C tomorrow, cloudy and wet on Sunday.
* Christchurch: Fine tomorrow with temperatures into the high 20s, rain and cooler temperatures on Sunday.
* Dunedin: Fine becoming cloudy tomorrow with a high of 21C, rain developing Sunday.
