Why Does New Zealand Always Get One Final Cold Snap Before Spring?

Early August brought an Antarctic polar blast across New Zealand's South Island, dropping snow to sea level, closing roads around Dunedin, and pushing temperatures in Tekapo and Mount Cook Village down to minus 7 and minus 8 degrees overnight. Hamilton and Taupo recorded lows around 8 degrees below average for the time of year, and MetService reported frosts reaching as far north as Northland. If this felt familiar, that is because it is: New Zealand tends to get one sharp, late cold snap almost every year in the final weeks before spring. Here is why it happens, and what it means for how you dress and heat your home until the weather actually turns.

In this article

• What happened in New Zealand's August cold snap?
• Why does this happen almost every year?
• How cold does it actually get, region by region?
• Does a late cold snap mean spring is delayed?
• How do you get through the last cold snap comfortably?
• Frequently asked questions

What happened in New Zealand's August cold snap?

A mass of Antarctic air pushed north over the South Island, bringing snow to near sea level across the eastern South Island and icy conditions that forced road closures and disrupted schools. Dunedin, the South Island's second largest city, saw snow settle on city streets, and police urged residents to avoid travel because of icy roads after a number of crashes were reported. MetService described the outbreak as likely to produce the coldest morning of the winter for many parts of the country, with the cold expected to persist for a couple of days before easing.

Why does this happen almost every year?

New Zealand sits close enough to Antarctica that cold air masses can push north and briefly override the milder, more changeable westerly weather the country usually gets through late winter. These polar outbreaks are more likely in the final weeks of winter because the temperature contrast between the deep Southern Ocean cold and the slowly warming NZ landmass is at its sharpest, which helps drive the cold air further north than usual. It is a genuine weather pattern, not a myth: forecasters and climate records both show that some of the country's coldest recorded temperatures happen in late July and August, not in the depths of June.

How cold does it actually get, region by region?

The scale of a late cold snap varies significantly across the country. The table below reflects the pattern seen in this August's outbreak.

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Does a late cold snap mean spring is delayed?

Not officially. New Zealand's spring begins on 1 September regardless of what the weather is doing that week, and the astronomical and meteorological calendars do not move for a cold snap. What a late outbreak does mean is that the transition into spring is rarely smooth. Warmer, more settled weather usually arrives gradually through September rather than switching on overnight, and it is common for a further cool change or two to arrive even after the calendar says spring has started.

How do you get through the last cold snap comfortably?

The most effective approach is not to overhaul your wardrobe or heating for what is usually a short, sharp event lasting a few days. Instead, keep a scarf and a throw within easy reach so you can add warmth quickly without turning the heating up. A kid mohair scarf protects the neck, which loses heat quickly, while a throw over a chair, sofa or bed adds an easily removable layer of warmth that does not commit you to a hot, stuffy room once the cold snap passes.

Frequently asked questions

Is New Zealand's August cold snap unusual?

No. Late-season Antarctic outbreaks are a recognised weather pattern in New Zealand and happen most years to some degree. What varies year to year is the intensity and how far north the cold air pushes.

When does spring officially start in New Zealand?

New Zealand uses the meteorological calendar, where spring runs from 1 September to 30 November, regardless of the weather on any given day within that window.

Why does a cold snap in August sometimes feel colder than one in June?

Ground and building temperatures have often had weeks to gradually warm through late winter, so a sudden cold outbreak in August can feel like a sharper contrast than the same temperature drop in the depths of June, when everything is already cold.

Should I wait until spring to put winter throws and scarves away?

It is worth keeping them out until well into September. A late cold snap or two after the official start of spring is common enough that packing warm layers away too early usually means digging them back out within a few weeks.