La Niña's gone; wild and unruly arrives


We've got hot temperatures, we've got cold temperatures, freezing temperatures, ice, snow, hail, rain - and even a few rays of sunshine. And one very confused weather pattern.

This time last week 15 towns and cities across New Zealand were on track to record their warmest May on record. By the end of the weekend just three were still in with a chance. Yesterday, they too fell out of the running.

And now there are new records being set and winter hasn't even officially started.

The typically sub-tropical Whangarei - the same town, that as of yesterday was tracking for its 4th warmest May on record, registered 0.8°C this morning, its coldest May temperature since 1976.

Auckland, Hamilton, Whangarei, and Thames were all colder than Christchurch and Dunedin last night. But the coldest temperature of the year so far was in Ranfurly and Middlemarch where it was -6.0°. It hasn't been that cold anywhere in the country since last September.

NIWA meteorologist Ben Noll says the weather switch was actually flipped at the beginning of April.

"For months we'd had a La Niña weather pattern which brings more warm northerly winds our way. Then it was like the rug was pulled out from underneath this global climate driver and we got something completely different."

Mr Noll says we are now in limbo—neither La Niña, nor El Niño—which means a lot of ups and downs, and exposure to more variable weather.

"Mother Nature dances to the left, dances to the right and then takes a misstep—we're seeing it all at the moment."

Tonight will be similarly cold across the country and Mr Noll is expecting more near records—in Whangarei’s case, it may break the coldest May temperature record of 0.6°C.

The silver lining, of course, is the early, deep snow packs down south but Mr Noll says the only certainty about all this uncertainty is that it's not an indicator of winter as a whole.

Mr Noll says conditions will turn a bit milder at times during the first half of June and we're not necessarily in for a winter with regular record-breaking cold, but the periodic sharp cold snaps that we've seen may indeed continue.

Check back on Thursday when NIWA releases its winter climate outlook.

Research subject: Climate