Whether you’re a fan of windy weather or not, the current spell of westerlies is continuing to drive temperatures well above where they should be for the middle of winter.

“July is typically when winter ‘sets in’ and yet the current wind flow is helping boost temperatures into late teens and unofficial reports of low 20s in some eastern areas” says head weather analyst Philip Duncan.

“While the westerlies affect the South Island, a sub-tropical low to the north is also helping funnel down warmer air over northern New Zealand, so many parts of the country are well above average whether that’s daytime highs or overnight lows”.

In some parts of the lower South Island overnight lows have gone from -6 a few days ago to +5 this week.  Or from freezing to double digit overnight lows.

The warmer weather is mostly as a result of the westerly winds in the Southern Ocean surging over the South Island as high pressure mainly retreats to northern areas – allowing these winds to surge northwards.

But despite northern and eastern areas climbing into the mid to late teens the spell of warm weather is unlikely to last. 

WeatherWatch.co.nz provides monthly forecasts to dairy giant Fonterra, and last month we picked a ‘potential cold snap’ around the middle of July.  It’s looking less significant now, but certainly we still see winds turning to cooler sou’westers as of early next week – but no signs of a major winter outbreak.

Instead Christchurch will slip from highs of around 17 degrees this week, to 12 by Monday.  Dunedin slips from highs around 14 this week, to 10 next week.

But the cooler south west change next week won’t have a dramatic effect on northern New Zealand.  Western areas, including Auckland, will sink back to highs in the low teens but overnight lows may still remain around the 10 degree mark generally speaking.

A high will slowly move in next week which may see frosts slowly return to sheltered parts of both islands

Showers look as though they may return to eastern parts of the North Island next week too, caught up in that same cool change which will be more of a south east wind flow by midway through next week for the North.

– WeatherWatch.co.nz