Thunderstorms are set to rumble across the North Island today before damaging gales blast the top half, and snow falls to low levels across central and southern New Zealand.
An icy cold snap straight off the Southern Ocean is due to sweep over the entire country.
Both islands are expected to feel the wrath of a wintry tempest bringing thundery squalls, strong winds and snow.
A strong wind watch has been issued for Auckland north from tonight and a heavy snow watch is in force for the top of the South Island for Sunday.
2️⃣0️⃣0️⃣
— MetService (@MetService) August 5, 2021
That's the number of lightning strikes over the Tasman and Nelson regions since 9pm last night⚡
More thundery weather today, especially for the NI, though not everyone will get it
Read all the details at https://t.co/BZWb7ZPiRd ^MM pic.twitter.com/YNygI8Ak7y
Southwest winds are expected to ramp up to severe gale tonight and last until daybreak, giving northern regions a second round of wild weather in days.
As the first of two major weather systems reaches our shores, lightning strikes have already illuminated skies over western regions of the North Island, and forecasters warn the storms will last through until later tonight.
MetService has warned the squally cloudbursts could be laced with hail up to 10mm in diameter and powerful 90km/h gusts.
Thunderstorms are expected to spread across the rest of the North Island and top of the South Island across the day.
A low pressure centre sweeps across the upper North Island tonight, cranking up those southwesters💨💨
— MetService (@MetService) August 5, 2021
Gusts of 90 km/h are possible for parts of Auckland and Northland, which are under a Strong Wind Watch🔸
^MM pic.twitter.com/Q0yNIqCVyG
MetService is advising motorists to take extra care on roads tonight and to tie down objects that could become airborne as a low pressure centre is due to sweep across northern regions cranking up strong southwesterly winds.
Weatherwatch.co.nz said blustery conditions were expected to continue across the upper North Island on Saturday, with temperatures pushing near 20C tomorrow before dropping to single digits on Monday.
On Sunday the weather will take a chilly turn, with heavy rain across the southern and central districts and snow down to low levels.
Alpine passes across the South Island are expected to be affected by the coming snow. There are road snowfall warnings currently issued for Lindis Pass, Crown Range and Milford Rds. Up to 15cm of snow is expected to settle on the road near the tunnel.
MetService forecasters are warning snow will be falling down to snow levels across the South Island and parts of the North Island.
The Central Plateau and Tararua Range is expected to be affected. Farmers are being warned to make necessary precautions for livestock potentially exposed to the cold snap.
"There's quite a cold air mass in circulation. We see that snow reaching to lower levels than we would normally see," MetService forecaster Mmathapelo Makgabutlane said.
The biggest snowfall is expected to happen overnight on Saturday.
Weatherwatch is warning of a second surge of gales overnight Sunday, as the main cold blast moves up New Zealand. Severe gales are possible in coastal areas.
That's led to a warning from Counties Power, which says the high winds have the potential to bring down trees and branches on power lines, as 110 km/h gusts are set to lash the storm-battered region early Monday.