Enjoy the sunshine while it lasts is the message as Tropical Cyclone Gita edges closer to New Zealand, bringing gusts of up to 200kmh and potential flooding.

MetService meteorologist Brian Mercer said the country should experience generally fine weather over the next few days.

"My message is to make the most of the weather while it lasts, before the cyclone comes through."

The latest charts from Fiji Metservice show Tropical Cyclone Gita, which ravaged parts of Samoa, Tonga and southern Fiji this week, now passing below New Caledonia.

It will enter the Tasman Sea over the weekend and could hit New Zealand on Tuesday or Wednesday next week.

"But there is still a lot of uncertainty in the models," says Mercer. "It could come earlier or later, even Monday or late Wednesday.

"Exactly where it will hit is also uncertain."

The North Island will most likely be hit hardest, but if it stays west a bit longer it could also hit the south.

"We will be more certain about that in the coming days," Mercer said.

The Category 3 tropical cyclone will be an ex-tropical cyclone, and maybe even have downgraded to a Category 2, by the time it arrives in New Zealand, but it will still hold much power.

"Category 2 is still really powerful," Mercer said.

"We expect it to ease a little as it enters the relatively cooler waters of the Tasman Sea, but regain power as it goes through the extra-tropical transition, and New Zealand is right in the zone where that happens.

"There will be strong winds, with an average of about 100km/h, but with potential gusts of twice that," Mercer said.

"There will also be heavy rain and potential thunderstorms.

"People need to prepare. The heavy rain could induce surface flooding, so now is a good time to check drains before it arrives."

The Fiji Metservice is now tracking the cyclone, but once it comes past 25 degrees south, it becomes New Zealand's responsibility.

"We expect that to happen tomorrow or Sunday," Mercer said.

Those still struggling to cope with the extremely humid weather at the moment should not expect relief anytime soon.

"In short, the humidity is not going anywhere," Mercer said.

"Tropical, hot and moist air remains over New Zealand, and there is not going to be any significant change until the ex-tropical cyclone passes.

"Following that, a southerly change will bring cooler air over the country.

"It will be a welcome change."

Today will be mostly fine for the North Island, with just a little cloud and fog over Hamilton and Waikato, but that should burn away during the morning.

There will be a few showers and cloudy periods on the Kapiti Coast also.

Tomorrow is expected to be sunny for most of the island, especially on the East Coast.

A front has begun moving slowly up the South Island, starting in Fiordland and Westland, where a severe weather warning is in place.

"About 120-150mm of rain is expected there by 3pm tomorrow," Mercer said.

"It is raining a bit there now but it is expected to really set in this afternoon, with potential thunderstorms."

Small patches of rain could spread over to Invercargill and Dunedin, but most of it will fall in Fiordland and on the Main Divide.

The rest of the South Island will have a slightly cloudy day, with gusty northwesterlies expected in Canterbury.

"But it should all come right by tomorrow morning with a fine day for most of the South Island."

Today's weather

Whangarei
Partly cloudy, chance morning shower. Northeasterlies. 27C high, overnight 19C.

Auckland
A fine day with some evening cloud. Light winds. 28C high, 20C overnight.

Hamilton
Fine apart from early fog. Light winds. 29C high, 16C overnight.

Tauranga
A fine day, but becoming cloudy tonight. Light winds. 27C high, 19C overnight.

New Plymouth
Fine apart from some morning cloud. Northwest breezes. 24C high, 18C overnight.

Napier
A fine day. Light winds, tending northerly from afternoon. 26C high, 18C overnight.

Wellington
Cloudy at times, and chance light showers in the north. Strong northerlies. 24C high, 19C
overnight.

Nelson
Fine spells, but chance evening showers. Northerlies. 25C high, 19C overnight.

Christchurch
Dry with increasing high cloud. Northerlies. 29C high, 18C overnight.

Dunedin
High cloud thickening. Northeasterlies. 25C high, 15C overnight.