Cyclone Oma may merge with southerly change to create massive weather system - forecaster

Two large weather systems may merge over New Zealand later this week, bringing wild wind and heavy downpours of rain to northern regions.

Meteorologists remain unable to predict whether Cyclone Oma, a category three cyclone currently moving past the northern tip of New Caledonia, will hit New Zealand.

NIWA forecaster Chris Brandolino suggests there are two possible scenarios, with both ending with a likelihood of significant rain and wind for Aotearoa.

"One scenario has [Cyclone Oma] going towards the Queensland coast, kind of just loitering out for the next several days, not really making it down to New Zealand," he told The AM Show on Tuesday.

Mr Brandolino said, under that scenario some "moisture" from the cyclone will peel off and hit New Zealand's northern regions, with another incoming weather system adding to the wild weather.

"That scenario also includes a separate weather system which comes Sunday or Monday, a southerly change. That brings some pretty good wind or rain for New Zealand".

The second scenario would see Oma making its way to New Zealand and "merging with the aforementioned southerly change".

That could create a massive weather system over the country, with Mr Brandolino saying the "atmospheric synergy" would produce something that was "greater than the sum of its parts".

"You get a much larger system - either scenario is probably going to produce some pretty significant weather."

Mr Brandolino's forecast reflects comments from Weatherwatch on Monday that suggest this coming weekend could be the wettest yet this year.

"The weather will get worse from Friday, and we'll see some rain which is great news with all the fire bans and water restrictions we've been seeing," said meteorologist Lisa Murray.

Ms Murray and Mr Brandolino's advice is to keep up-to-date with weather announcements in order to be prepared in case severe weather hits.