"Obviously we've had some quite turbulent weather yesterday with some heavy rainfall over the North Island and the low that caused that is just moving away to the east today so it's just a general easing trend today so it's a nice, very short reprieve for some people.
"Then we have what we call a complex low, or broad area of low pressure that's moving on to the country tomorrow from the Tasman Sea.
"What that means is it's actually hanging around the whole weekend unfortunately. Rain is going to start spreading from the north again, sort of like what we've seen but it sticks around longer."
However, she said it wouldn't be a complete whitewash in Auckland and there would be a few breaks in the rain.
"There will be some gaps or breaks where it won't be so heavy ... but I would say definitely Aucklanders check forecasts and the rain radar because it looks like they will get rain in the first front late on Saturday and then will get another burst late on Sunday as the low pressure starts moving further north.
"It's a very messy situation and no one is going to escape a bit of rain.
"It's going to be very windy with that first front that's moving over Northland and we will see strong northeasterlies for a period of time with that as well, so people need to watch out for that on Saturday."
The southerly change would see some marked changes in temperatures; Christchurch will go from 22C on Saturday to 13C on Sunday.
"It makes it very interesting as there will be huge differences in temperatures for the North Island going down to the south."
Wellingtonians were being warned to expect a "nasty" Sunday, she said, with heavy rain and strong winds.
"It's going to be one of those shockers of a day for Wellington city."
The southerly change was also expected to bring a sprinkling of snow down to 800m in the Southern Lakes area on Saturday afternoon and to 1000m in the Canterbury high country into Sunday.
By Sunday the low pressure system would reach the middle of the North Island, she said.
