Humid, wetter summer tipped for upper North Island

A more humid, potentially wetter summer season is on the cards for the upper North Island - but that doesn't mean people should go cancelling their Coromandel holiday plans.

A new outlook shows New Zealand is at a "near normal" risk of catching the fall-out of tropical cyclones over the coming November to April season.

While an ex-tropical cyclone typically edges within 550km of the country around once every season, bringing with it significant wind, waves and rainfall, there was a possibility of more than one rolling in from the southwest Pacific this time.

Current background climate conditions suggest that if a system comes close to New Zealand, there was a greater probability of it passing east of Auckland and the North Island.

Under the influence of neutral to weak La Nina conditions, meteorologists have predicted between eight and 10 named cyclones hitting the southwest Pacific, with five to six of them expected to be severe.

"For New Zealand, the key message is the fact that the seas to the north of the country remain quite warm," said meteorologist Georgina Griffiths of MetService, which annually works with the National Institute of Water and Atmosphere (Niwa) and other agencies on the outlook.

"North of Taupo, you may expect more of a La Nina-like flavour, which would include some sub-tropical rain at times, long dry spells in between, and warmer, more humid, conditions.

"So we may see quite a different season this year compared to last year and the year before.

"It has a lot more easterlies - that's what we are seeing for the next three months, and we've already seen a really wet run for the North Island for the last few weeks."

The cyclone report followed Niwa's latest seasonal outlook for the next three months, predicting that temperatures were "very likely" to be above average for the northern half of the North Island, with rainfall totals equally likely to be either near or above normal.

But Griffiths added that those already planning Christmas camping holidays shouldn't panic.

"A climate forecast isn't particularly helpful from an 'am I going to get wet in my tent' point of view," she said.

"As always, you are just going to have to listen to the actual weather forecast across the core two-week holiday period."

The tropical cyclone overall seasonal outlook for the number of named storms interacting with an island group over the 2016/17 season. Image: NIWA

By contrast, Australia was expecting more cyclone-driven activity this season, particularly around the country's northern coastline where waters were warmer.

Based on a 30-year average, around 10 cyclones could be expected in the southwest Pacific region each season.

Activity was predicted to be normal for most Pacific Island nations, but elevated activity was expected in the west of the region in and near the Coral Sea.

At least six storms were anticipated to reach at least Category 3, with mean wind speeds reaching a hurricane-force 118km/h, while four could reach at least Category 4 strength, with mean wind speeds of 159km/h.

But meteorologists weren't ruling out the chance of Category 5 cyclones, where wind speeds could even hit 196km/h.