MetService outlook: Warm weekend, South Island rain and tropical system risk

As we edge closer to the depths of autumn, this weekend is set to deliver sweltering temperatures near 30C and bursts of heavy rain, with a developing tropical system looming.

MetService meteorologist Paris Marshall told the Herald the tropical system brewing to the northeast could impact the country next week.

She said MetService is tracking it “vigorously”.

“There’s a lot of uncertainty, and we don’t want to create fear at the moment ... it hasn’t become a tropical cyclone yet. There is a moderate chance that it will,” Marshall said.

She said if the system does reach New Zealand, it is expected to hit mid next week.

MetService said a slow-moving cold front is set to approach the West Coast of the South Island early this morning, bringing heavy rain to Fiordland and southern Westland.

Residents further north are set to stay dry, with the front likely to weaken as it tracks north.

Marshall said another front is likely to reach Fiordland later, while the rest of the country remains under a large area of high pressure.

“The second front moves northeast over the bottom of the South Island on Sunday, followed by a cool southerly change,” she said.

MetService has a heavy rain watch out for Fiordland and Westland between Doubtful Sound and Haast from 9am this morning to 3am Saturday morning.

MetService meteorologist Michael Pawley said a “ridge of high pressure holds strong over the North Island until Monday”.

Sizzling temperatures

After the cold start to this week, MetService said temperatures will rise again for the eastern parts of the South Island over the next few days.

Dunedin and Ōamaru are forecast to reach a sizzling 27C today, and Alexandra is expected to rise to 29C tomorrow.

MetService said the winds will turn southerly on Monday, and these warm temperatures will likely “come crashing back down to the mid-teens”.

Marshall said Alexandra was expected to reach the highest temperature on Saturday and then the coolest maximum temperature on Sunday.

Aucklanders should expect 24C as a maximum and 15C as a minimum for both Saturday and Sunday.

On Monday, a southerly change will sweep up the east coast. Photo / Michael Craig

Southerly change and developing tropical system on the way

On Monday, MetService said a southerly change will sweep up the east coast, bringing showers.

“A few showers can also be expected for Taranaki Anniversary day as the weakening front moves on to the North Island,” MetService said.

In the tropics, there is still plenty of activity to the north of New Zealand.

Over the next few days, MetService said a developing tropical system has the potential to move from the Coral Sea towards the Queensland coast.

“From there, some early indications bring this system back eastwards closer to our shores later next week,” MetService said.

With still plenty of variation in the potential path and movement of this system, the impacts on New Zealand are still not set in stone.

MetService said it may pass to the north of the country, and MetService meteorologists will continue to monitor the tropics.

Sign up to The Daily H, a free newsletter curated by our editors and delivered straight to your inbox every weekday.