Why Canterbury might have to wait for the second half of winter for snow

Friday, 5 June 2026

Merino sheep in snow near Lake Coleridge in the Canterbury High Country after a snowfall in early June last year. Such conditions have not appeared so far this year.

Paul Gorman is a senior science writer.

ANALYSIS: It’s been so warm this past week, you’d be forgiven for forgetting it’s now winter.

It’s also been incredibly wet in some places in recent days. Earlier this week, some places in the Tasman District reported 400-500mm of rain across about 60 hours, with the station at Paradise Peak peaking at 724mm.

At the same time, it has been exceptionally dry in eastern parts of the South Island especially, where Christchurch had its driest May on record, with just 5.8mm of rain at the airport. While in the deep south last month they had a real run of heavy frosts.

Springfield in Selwyn, covered in snow in August 2022. Colder weather should be on the way from next week, though it is unclear whether snow is on the horizon.

So, what’s going on? Shouldn’t the whole country be getting cold? As the length of the days contract towards the winter solstice at 8.24pm on June 21, with the shortest day on June 22, you’d normally expect a sprinkling of frost across both islands and snow on the peaks.

By this weekend we should finally be on the other, cold, side of the recent persistent area of low pressure with its mild air and moisture. Snow lovers may – only may – have something a bit more wintry to look forward to, though there’s no strong signal for any low snow.

Forecasters are sharpening their snow-prediction pencils ahead of the next four months, when our southerlies become bone-chilling and capable of bringing snow down to the lowest levels.

Predicting snowfall accurately can be a tricky business.

Accurately predicting snow in a mountainous country surrounded by often warmish oceans is like the holy grail of weather forecasting.

The coldest airstreams are often too dry to bring the heaviest snow, which generally, and somewhat bizarrely, arrives from a much warmer, wetter airmass being undercut by a cold layer.

Snowflakes, like anything made of ice, are incredibly sensitive to small rises in temperature and changes in altitude. At sea-level it might be 2C with steady sleety rain, while just 100m up a neighbouring hill it is 1C with heavy wet snow falling and settling.

Predicting such nuances accurately, especially if the snowfall is likely to be disruptive or dangerous, is extremely tricky.

With El Nino on its way, it is unclear whether this winter will bring snow.

MetService has never issued a top-level red warning for heavy snow in the seven years since they were introduced.

In fact, warnings for snow are much less common than for heavy rain or severe gales. Last winter, MetService only broadcast three snow warnings, including an early one at the start of May and a late one in October.

Last month, the forecaster held a refresher workshop on snow, going over the weather patterns to watch out for and sharing tips about general winter forecasting.

Meteorologist John Law said there weren’t any big changes coming about how the service communicated snow predictions, but it was important forecasters had all the tools and knowledge they could at their fingertips.

Meanwhile, Canterbury’s specialist forecaster Blue Skies Weather has changed the way it handles snow, with a new regional service which gives a weekly Monday snow outlook, and updates if necessary, along with detailed predictions from four days before any snowfall and post-event analysis for major dumps.

Chief forecaster Tony Trewinnard has built “The White Stuff” to pick up snow patterns as early as possible and has “fine-tuned the predictions for our Canterbury geography, and incorporated patterns and experience from past events”.

The jury is still out, though, on how snowy the winter might be.

A smoky haze at One NZ Stadium during last Friday’s rugby match between Crusaders and Hurricanes, partly caused by an inversion layer in the building.

Earth Sciences New Zealand’s winter outlook released this week warns the approaching strong El Nino may not generally be conducive to much snow other than in the south, though with a prediction of more southwesterly winds and rapidly fluctuating temperatures from the second half of winter that could see snow spreading further north at times and to lower levels.

Next time we’ll look at some of the most disruptive snowstorms to affect New Zealand in the past few decades.

Indoors kind of weather

In the last column we heard about anticyclonic gloom and how when temperatures get warmer with height it forms an inversion, a lid which keeps murky stuff trapped lower down.

We saw a great example of this inside Christchurch’s One New Zealand Stadium at Te Kaha during the recent Crusaders v Hurricanes game.

Smoke from fireworks at half time hung about for part of the second half because it was stuck under an inversion caused by higher temperatures at the top of the stands than lower down.

Just goes to show the weather operates at many different scales in the most unlikely places.

Need a stadium forecaster?