NZ weather: Power outages possible as 'strong winter blast' brings 90km/h winds, 'extreme' wind chill as low as -15C in mountains

Wind gusts of 90km/h could cause power outages in Northland and parts of Auckland on Friday night ahead of a "strong winter blast" causing snow, thunderstorms and plunging temperatures this weekend.

The gales, which will move into northern parts of New Zealand over the next 24 hours, are not expected to be as intense as they were when thousands of homes lost electricity earlier this week.

But WeatherWatch says there's still a possibility of power outages in Northland and rural north-west Auckland as blustery winds of 90km/h and over set in. MetService has issued a strong wind watch.

"While there are some similarities to Tuesday's set-up, the worst of the winds this time look to be more focused in Northland and actually fade out to some degree the further south you go over Auckland region," WeatherWatch says.

"A few weather-related power outages are possible overnight tonight in Northland and perhaps rural north-west Auckland as winds gust 90km/h and may be higher in some isolated coastal or higher altitude spots.

"Winds in Auckland city don't look as intense but Saturday will be blustery in some areas."

Vector told Newshub it is continuing to monitor the weather on Friday afternoon, and have crews available to attend any outages if required.

The winds on Friday and Saturday are just a precursor for what's to come though, according to WeatherWatch.

The forecaster warns of "gales, thunderstorms, snow, sleet, rain [and] wind chill" moving up the country beginning on Sunday, with dramatic temperature drops as a result of the "strong winter blast".

"By Monday everyone in New Zealand has a temperature drop of a few degrees to over 10C down. Hastings has a high of 17C on Saturday and a high of 8C on Monday.

"Daytime highs across Southland, Otago and Canterbury will be down to just +5 or +6C on Sunday and Monday with windchill below zero in exposed places.

"Wind chill will be extreme in some higher alpine areas with -10 to -15C expected through the mountains on Monday. At sea level wind chill will get down to around -3C in some locations and may linger for 24 to 36 hours."

Snow flurries are expected low down in the South Island, with WeatherWatch warning of possible road closures in both islands.