The upper North Island is being warned to prepare for damaging winds, heavy rain and surface flooding as a large low makes landfall on Wednesday.
As the low moves towards New Zealand, it's dragged down moisture from near Papua New Guinea - and it means some areas could be hit by torrential rain.
"Check out that koru-like low!" NIWA says, showing a graphic of the system.
"It’s dragging heaps of moisture toward New Zealand. The result will be some heavy rainfall in the northern North Island on Wednesday-Thursday. Look out for localised areas of surface flooding!"
MetService has issued a heavy rain warning for the Far North, which kicks off around midday today. A heavy rain watch is also in place for the Auckland region and the Coromandel as the intense rain-band moves south.
"The orange heavy rain warning kicks off from 11am on Wednesday and drifts southward into Thursday with a small possibility of localised downpours," a post on the forecaster's Facebook page reads.
"The rainband is associated with some gale northeasterlies and the greatest risk for damaging winds is through the Auckland region from late on Wednesday."
NIWA says weather systems like the one arriving on Wednesday will likely be "semi-regular visitors" for the next few months.
"The seasonal outlook calls for near normal rainfall in the north of the North Island and normal or above normal rainfall in the east of the North Island. That's a trend in the right direction."
