Hot and dry El Niño-fuelled summer on the cards out east after 'wintry' spring

East Coast beaches could be the places to be this summer with an El Niño weather pattern increasingly likely. File photo / Jason Oxenham

The east coast might be the place to be this summer with climate patterns indicating it could be a hot and dry one.

NIWA meteorologist Ben Noll said the chance of an El Niño weather pattern this summer was increasingly likely.

During an El Niño, caused by warmer than average sea temperatures in the central and eastern Pacific Ocean, New Zealand typically experienced stronger or more frequent winds from the west in summer.

This meant drier-than-normal conditions in the east and more rain than normal in the west, due to the barrier effect of the Southern Alps and main North Island ranges.

Noll said while El Niño was often attributed with drought on the east coasts of both the North and South Island, it was too early to say how severe this one would be.

"The chances of an El Niño pattern in the summer months increases to about 78 per cent, so more than double the normal chance.

"But the one coming is likely to be on the weaker side, maybe not the traditional El Niño. It is very premature to start talking extreme dryness."

Noll said there were always three possible weather patterns: La Niña, El Niño, or neutral.

La Niña occurred when ocean temperatures in the central and eastern Pacific Ocean were below average, El Niño when they were above, and neutral when they were average.

Right now ocean temperatures were about 0.4C above average, and had been for some time, Noll said.

"In the last few months we have seen the ocean temperatures rising. At 0.4C it is still neutral, but it is slowly heading in the direction of El Niño."

Those same warm ocean temperatures were linked to the record-breaking heatwave hitting Japan, where dozens of people have died from heat stroke.

How strong El Niño would be depended on how above average the ocean temperatures were, and where they were in the Pacific.

Before then, the country was in for a "changeable" period, Noll said.

"It looks like August will continue with some spring-like warmth that began in July."

However, as we moved into spring, and assuming the El Niño pattern continued, there could be some more cold snaps.

"That El Niño pattern could mean more southwest winds in spring, so they could bring some wintry cold snaps in September and October.

"So while it may seem like we are already into spring, hold up because Mother Nature may still have some tricks up her sleeve."