Weekend weather: Strong winds forecast, MetService warns damage possible

Strong winds will continue to bluster New Zealand this weekend, with a chance of damaging trees, powerlines and unsecured structures, as a front begins to move north over the country.

MetService meteorologist Stephen Glassey says the weekend will start on a relatively calm note before northwesterlies quickly strengthen over the South and lower North Island as the next front approaches.

“A combination of high pressure to the north of New Zealand and a deep low-pressure system over the Southern Ocean will help create some very strong winds,” Glassey said.

MetService says winds are looking particularly vigorous over central New Zealand late Saturday and Sunday, and could damage trees, powerlines and unsecured structures like trampolines.

Multiple high wind events are expected over the coming days for parts of NZ.

Here are the odds of 100+ km/h wind gusts from our ensemble modelling.

🔴 high
🟠 medium
🟡 some

Sunday looks to be a particularly windy day with widespread damaging wind gusts distinctly possible. pic.twitter.com/D9NBeTovkX

— NIWA Weather (@NiwaWeather) September 13, 2023

Sunday will pack the most damaging winds, making driving potentially hazardous, especially for high-sided vehicles and motorcycles.

A raft of strong wind warnings are in place throughout the weekend from Wairarapa to the bottom of the South Island.

Strong wind watches are also in place for Horowhenua and the Kapiti Coast, Tasman northwest of Motueka, Canterbury Plains and Christchurch including Banks Peninsula, Otago, Fiordland south of Milford Sound, Clutha and Stewart Island.

On Thursday, winds in Kelburn, Wellington recorded maximum winds of 102km/h for the first time since March.

Yesterday winds in Kelburn cracked 100 km/h for the first time since March💨💨💨

This weekend winds crank up once again, with the strongest winds expected on Sunday pic.twitter.com/h5dRikjLXJ

— MetService (@MetService) September 15, 2023

The rest of the North Island, from Manawatū northwards, can expect a mainly fine and calm Saturday, before the strong winds arrive on Sunday.

Auckland and the far north are expected to miss the horrendous weather this weekend; Saturday’s forecast is sunny with light winds before westerlies begin to pick up on Sunday and Monday. Wind speed isn’t predicted to get above strong.

“Conditions should be fine with light winds for the NRL play-off match between the New Zealand Warriors and the Newcastle Knights at Mt Smart Stadium in Auckland on Saturday evening,” Glassey said.

It’s not all doom and gloom, however. The strong northwest flow over the country will also help create some warm temperatures in eastern areas.

📈 Next Tuesday-Wednesday, the jet stream looks to transport some unseasonably warm air into Aotearoa/New Zealand, particularly in the east of both islands 🌡️

☀️ With the rā (sun) shining, high temperature records may fall at a location, island, or even national level! pic.twitter.com/Pd2xPtsECF

— NIWA Weather (@NiwaWeather) September 14, 2023

Afternoon temperatures are expected to exceed 20C in Gisborne, Hawkes Bay, Marlborough and Canterbury on Sunday and are forecast to hit a summery 25C in the east next week.

Niwa Weather says mid-next week the jet stream will bring some “unseasonably warm air” in from northern Australia.

“When air coming from the northwest loses its moisture as it moves over ranges, it warms as it descends down the other side. This is known as the Foehn effect,” MetService says.

Looking ahead to next week, strong winds are likely to continue to affect parts of New Zealand, although they ease somewhat for most of the country on Monday.