Big wet to become even wetter over next nine days

Forecasters say 'wet events' such as the one that caused the weekend's flooding in the Bay of Plenty will continue for the rest of this month. Photo / Daily Post

Waterlogged areas of the North Island won't get an immediate reprieve as forecasters warn of more "wet events".

As the eastern Bay of Plenty cleans up after weekend rainfall caused flooding, slips, road closures and evacuations, at least three significant wet-weather systems are expected to dump more rain on the island over the next nine days.

The rain is expected to arrive tonight for many northern and western areas, while a brief cold snap is predicted to hit the lower South Island.

"On Wednesday a cold southerly will briefly bring 24 hours or so of winter-like weather with snow to fairly low levels," said Weather Watch analyst Philip Duncan. "At this stage it does not look to be a severe event."

Another large low is expected to move in from the west for Friday and the weekend, bringing the potential for more rain warnings. The MetService has put Taranaki and Eastern Bay of Plenty at risk of heavy rain in that time.

Long-range computer models foresee another potential "rain maker" system about the middle of next week.

Gerard Van Beek, of the Bay of Plenty Federated Farmers, said the eastern bay had "taken quite a hiding" at the weekend and more heavy rain on the sodden turf would be a real worry.

A further 10 to 15mm of rain could be helpful in washing river sediment off the pastures, but more than 20mm would raise the prospect of rising river levels and flash flooding again, he said.

Mr Duncan said the series of lows and fronts coming in from the west pointed to a shift from El Nino to La Nina weather patterns.

"This means more of the warmer weather but it also means more heavy rain and an increased risk of flooding in the North Island and east coast of both islands."