Weather Watch: Shift to bring an end to warmth and rain

Northerlies brought spectacular rain in Otago. Photo / Doug Sherring

New Zealand's weather pattern is making a change today - and it could be a significant one. The northerly flow that has dominated so many regions over the past few weeks is now turning to a westerly, and by the end of this week we may be seeing more evidence that winter is brewing.

The northerly flow has been unusual in its longevity. It created record-breaking heat on the West Coast, with temperatures smashing previous May records.

In fact, the highs so far this month have certainly been high. Two days reached 26C, one reached 25C, five reached 23C and one 22C - affecting nine separate regions in total (not just one place over and over again, although Gisborne has taken the most national highs this month).

The northerlies, which have been in place since Easter weekend, have been associated with some spectacular rain events from Northland to Otago. Parts of Hawke's Bay had more than three times their average April rainfall in just two days. And many parts of Otago received their entire monthly rainfall in 12 sodden hours last weekend, the Herald reported, pushing Alexandra to possibly its wettest May ever.

A slip in Dunedin gave a bit of a shock to resident Lloyd Hiscock, who had heard strange noises: "I heard these thuds. After about the third thud, I got up to look and then there was this almighty bang."

The hill behind the house had collapsed, bringing down tonnes of dirt against the back of Hiscock's house.

"I didn't sleep well after that."

La Nina is delivering a final, powerful punch to New Zealand in the form of wet north to northeast flows.

But that may be all about to end. Computer models for the week ahead show a solid west to southwest change. Certainly more apt for May than solid northerlies.

By the end of the week, we may even be looking at a more wintry change to southerlies. There's still some uncertainty but one thing we can be certain of is that the tap for the relentless northerly flow has been turned off - at least this week.