A severe tropical cyclone bearing destructive winds and rain is expected to die down before hitting New Zealand this week.

Tropical Cyclone Zelia has strengthened to average wind speeds of 167km/h and gusts of 220km/h as it crosses the Pacific Ocean, putting it in line with a destructive Category 2 hurricane under the US Saffir-Simpson scale, weatherwatch.co.nz reported.

But the site's head weather analyst Philip Duncan said the eye of the storm had gone in recent satellite imaging, indicating it was subsiding.

While winds may reach severe gales in some places across New Zealand, they will not be "cyclone strength" and rain will be the greater problem, he said.

"Zelia has enough oomph to maybe bring flooding rains but this is not going to be a repeat of previous cyclones, such as Drena, Fergus and Bola"

"In saying that, as we always know with tropical systems, we need to closely monitor them and watch for particular rain bands that may cause flooding."

Tropical Cyclone Vania, which lashed Vanuatu and New Caledonia last week, is also expected to die down before hitting New Zealand, Mr Duncan said.

It too should be no worse than a normal low pressure weather system, despite projections it could bring heavy rains and flooding to Northland and Coromandel, he said.

"The positive is that they will move across New Zealand very quickly and be gone by Thursday. Most places will only have a day or two of off and on rain and some wind.

"But there is good news - the system is predicted to drop rain over thirsty farms in both islands."

Both systems are expected to hit New Zealand tomorrow or Wednesday morning.

Zelia is expected to pass over the North Island and potentially the upper South Island while the remnants of Vania will push into the South Island, weatherwatch.co.nz reported.

Only Norfolk Island, an Australian island 700kms north west of New Zealand with a population of 2100, could get hit hard by Tropical Cyclone Zelia, it predicted.

MetService duty forecaster Paul Mallinson also said both cyclones were "falling apart" and would not cause as much damage as the storm that hit New Zealand after Christmas.

"We can expect strong winds through the centre of the country on Tuesday and Wednesday, and heavy rains mainly in the central parts."

He said the weather systems would last only about 12 to 15 hours.

Meanwhile, most of New Zealand bathed in scorching temperatures yesterday with the top temperature of 34C recorded in Christchurch. Auckland reached a high of 26.

Mr Mallinson said yesterday's temperatures were likely to be repeated today.

"It's going to be a pretty settled day," he said. "A bit of a weak rain band is coming down to the upper part of the North Island later in the day.

But the rest of the country will have lighter winds."

The MetService has warned that solar UV rays will be extreme and advises staying in the shade between 11am and 4pm.