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Tuesday Newsfeed: Subantarctic air spreads up NZ, but the cold comes in from the east (+15 Maps)

Subantarctic air is moving up NZ, coming in from the east and not a direct southerly. This is due to a ridge of high pressure south of New Zealand extending out from a powerful anticyclone centred over Tasmania.

This powerful high will help nudge the low pressure zone over the Tasman Sea further northwards and the low then starts to weaken.

Heavy snow in the South Island set in overnight Monday and continues across Tuesday, and will start to head northwards. Heaviest snow is above 300m in the South Island but some flurries may go below 200m for a time.

Snow to sea level is not expected, although it may fall near coastal areas in the hills of Otago – and sometimes a downdraft can push some snow lower. Snow in NZ can be very borderline at sea level and it can easily change.

Flights and highways/roads may be affected by the weather, mostly in the lower half of the South Island and through the Southern Alps/alpine passes.

Cold air and windchill will be around zero degrees at the ‘warmest’ part of the day and this places a high risk to newborn livestock across much of the South Island and the eastern half of the North Island over Tuesday, and then further northwards on Wednesday.

Coldest air reaches northern NZ on Wednesday or Thursday but in a weakened state. Snow is likely along the eastern ranges as far north as Hawke’s Bay ranges although may not be a major event for Central Plateau. Still, some snow is likely for most ski fields across the country and a dusting across SH1 the Desert Road.

That powerful high pressure zone over Tasmania then moves into NZ by Friday and the weekend – further pushing the Tasman Sea low north of the country and causing it to mostly fall apart.

Then the frosts kick in.

By Thursday/Friday frosty weather may be the most widespread it’s been this winter in the South Island. The North Island will have more wind and cloud which limits the frosts there this week, but frosts are possible this weekend.


Keep up to date with MetService warnings and watches – they will continually be issued and gradually removed over the next few days.

Official MetService warnings & watches map as of 6am Tuesday. Click/tap for latest. It’s likely this map will next be updated by MetService on Monday night.

Get fewer nasty surprises and more local weather data than any other NZ forecaster in the latest FREE WeatherWatch App (incudes paid tier for weather alerts – and official MetService warnings and watches – pushed to devices covering multiple locations. You set the criteria!).



These maps are powered by Weatherzone – Infographics by WeatherWatch

Above/Below: Departure from Normal Temperature: In other words, for this time of year, how much warmer/cooler is it compared to what is normally recorded. The eastern half of the country becomes increasingly colder, but western and northern NZ still remain a bit warmer than average.

*These maps are from our official partners at The Weather Company.


Rainfall from Monday PM through to Sunday PM (GFS model). For the most part, this isn’t a major rain event but some pockets here and there may exceed 100 or 150mm in the coming days.


WeatherWatch.co.nz also recommends Lert Info to make sense of all your local alerts – not just weather. Lert Info is New Zealand’s only nationwide private emergency push alert service and collates all local advisories in your area into one place. Weather, roads, police, council, fire and more – they’ve got your local area covered.

Lert Info is independent of WeatherWatch and we’ve supported each other for well over a decade.


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