Tekapo, South Island cut off by snow
© GEORGE EMPSON
Tekapo, South Island was cut off by snow last month.
It may have been warm overnight this week, but New Zealand is currently experiencing its coldest winter since 2009.

MetService meteorologist Georgina Griffiths said not only has it been cold, the main centres have also experienced more rain than last year, with Christchurch sitting at 134 per cent of its usual rainfall at 551mm compared with 411mm.

However, just to confuse people even more - especially in eastern parts of the country - temperatures are expected to hit 18 degrees, even 20 degrees in Napier, this weekend.

"It has been enormously wet and cold, it's been a crappy year, basically. It's an unusual and extremely volatile year."

She said most towns were "running quite cool bar this recent four or five day warm blip".

"The temperatures for the first 60 per cent of the year, 220 days, Christchurch is running a full degree and a half cooler than this time last year. That might not sound much but actually when you get a year when it's 1 degree above the long term average you're almost into record territory."

Wellington and Auckland were each running 1 degree colder than last year.

"It may not sound like much, but it's very significant difference over a seven-month time period."

Last year was one of the warmest winters in New Zealand with June 2016 the third warmest June on record.

"Just the sheer difference from last year and the fact we haven't had a cold winter since 2009 for most places is pretty notable. Some places had a cooler winter in 2012 but for most parts of the country, 2009 was the last time we had a real cold winter and this has got shades of that.

"Although we've just had a warm blip as you've noticed, and the reason why people have noticed it is because people have gone 'Omg it's so warm' but we have run really cold this year."

The warm stretch is set to come to and end but not before Napier, Whangarei and Christchurch try and knock August's hottest day - 21.6 degrees - out of the record books, with each forecast for 20 degrees.

There were yet to be any records broken but during the warm stretch it had been "unusually mild".

"This is the coldest winter we have had in a long while - since 2009 for many regions. The difference in temperatures between last winter, which was incredibly warm, and this winter, has been absolutely noticeable on the wardrobe, and the power bill."

MetService duty meteorologist April Clark told the Herald earlier today most of the country was enjoying temperatures on average up to 4C warmer than usual for this time of year.

"It has been, on average, warmer, especially than what we have been having. The last couple weeks of July, pretty much almost every main centre was colder than average. So maybe that's why it's feeling so warm."

Although up to 4C warmer overnight "wasn't a huge amount" it covered the whole of the North Island and upper South Island.

"That's just the northerlies bringing warmer air in."

And it was set to continue with similar weather forecast over the weekend.

RAIN, RAIN, RAIN

Auckland rainfall so far this year - 902mm
Normal rainfall - 755mm
= 120 per cent of normal

Wellington rainfall so far this year - 995mm
Normal rainfall - 819mm
= 121 per cent of normal

Christchurch rainfall so far this year - 551mm
Normal rainfall - 411mm
= 134 per cent of normal

HOT, HOT, HOT

The hottest August temperature on record is 21.6 degrees. Napier and Whangarei are both forecast for 20 degrees, but Griffiths doesn't believe either town will beat it.

"This year, 2017, has been an extremely rough year, weather wise" - Georgina Griffiths, MetService.