Philip Duncan: Winter teasers see us scurrying for warmth

Christchurch pedestrians watch their step. Photo / Christchurch Star

Winter continues to tease us with frequent cold snaps brushing past New Zealand, mostly clipping southern regions of both islands.

The cold air has already created a number of frosts as far north as Auckland. This time last year the city had received none.

The weather pattern we have this winter is similar to that of last winter, but the persistent southwest winds of late are drying out eastern areas.

In March I predicted that frequent intense highs near Tasmania would put New Zealand at an increased risk of another polar blast this winter, such as the one we had last August. That one produced snow in the usual main centres but surprised many more as it blanketed Wellington and fell, unusually, in places such as Nelson, Palmerston North, New Plymouth and Auckland.

The usual risk for a nationwide snow outbreak like that is about 5 per cent each year. This year we think it's more like 30 per cent based on these very big highs around Tasmania and the big stormy lows southeast of the South Island. It's this setup that can produce polar blasts.

The flipside is there's a 70 per cent chance snow won't fall as far north as Auckland and Northland again this year.

The current southwest wind flow is a common one for New Zealand. Although it can howl through Auckland bringing plenty of clouds from the Tasman Sea, most other main centres fare well with the wind direction. Eastern Northland, Coromandel Peninsula, Bay of Plenty, Gisborne, Hawkes Bay, Wairarapa, Wellington, Nelson, Marlborough, Canterbury and even Otago can all have stunning weather when the flow over the country is southwest.

New Zealand has such a temperate climate that our winter is hardly a true winter, generally speaking. Alexandra is pretty much the only main centre whose winter daily high is below zero while at the other end of the country Aucklanders can wear shorts and T-shirts.

I once suggested that our spring and autumn should be four months long and summer and winter both two months. It wasn't a popular idea, but I was just highlighting how temperate our country is.

We do not experience extreme warmth or cold - despite being the country with four seasons in one day.