Are we in for another big, bad El Nino?

The severe drought in 1997 and 1998 cost New Zealand hundreds of millions of dollars. Photo / Christine Cornege

Is New Zealand really in for a big El Nino this summer?

That's the question meteorologists are keen to know, with a build-up of warmer water around the tropical Pacific vaguely suggesting the same indicators that preceded the horror El Nino of 1997 and 1998, which resulted in a severe drought that cost the country hundreds of millions of dollars.

Chris Brandolino of the National Institute of Water and Atmosphere (NIWA) said while it was premature to suggest the country was in for an intense El Nino later this year, his colleagues had observed some similarities between what was happening now and the prelude to the 1997/1998 event.

It was also possible that the El Nino, which is already underway in the tropical Pacific, could peak towards the end of the year and dissipate by 2016.

In New Zealand, the ocean-driven system typically brings cooler, wetter conditions, bringing higher rainfall to regions that are normally wet, and often drought to areas that are usually dry.

Farmers in the western, wetter parts of the country often faced significant damage to pastures from too much rainfall, and it was also harder for stock to thrive in the constant wet.

Those in the east, faced with dry conditions, needed to consider food availability for stock.

While an El Nino never really took off last year, despite the probability being high this time in 2014, a system was now being observed with sea surface temperatures continuing to warm across many areas of the eastern and central tropical Pacific.

A NIWA climate update issued today also stated cloudiness, rainfall and convection activity near and to the east of the International Date Line had intensified - features indicative of consolidating El Nino conditions.

The international guidance indicated that El Nino conditions would continue through winter and spring, and into summer 2015/16.

"The key question is will that warm water remain over the coming months or dissipate?" Mr Brandolino said.

"Typically, we see El Ninos peak in spring and toward the end of the year."

He noted that while the effects of El Nino could certainly be damaging here, the impact was felt much more severely in Australia.

Meanwhile, NIWA is predicting temperatures are most likely to be in the near average range for all regions of the country for the rest of winter.

Over the next three months, above normal pressures were forecast to the west of New Zealand, with below normal pressures expected well south, and northeast, of the country.

This mixed pressure pattern was likely to be accompanied by anomalous southerly-quarter wind flows, which was typical of El Nino conditions during the winter season in New Zealand.

Sea surface temperatures around the coasts of New Zealand were also expected to be near average for the coming three months.

Until spring, rainfall totals were most likely to be in the below-normal range for the north of both islands and the west of the North Island.

Elsewhere, it was equally likely rainfall would be either near or below normal for the east of both islands, while near normal rainfall was most likely the case for the west of the South Island.

Soil moisture levels and river flow were most likely to be below normal in the north of the North Island and the east of the South Island and about equally likely to be in the below normal or near normal range in the east of the North Island and the north of the South Island.

Below normal or near normal river flows were also equally likely or the west of the North Island.

In the west of the South Island, river flows were about equally likely to be in the near normal or above normal range, while near normal soil moisture levels were likely for the west of both Islands.

Across Northland, Auckland, Waikato, Bay of Plenty, temperatures were most likely to be near average, rainfall totals were most likely to be in the below normal range and soil moisture levels and river flows were most likely to be in the below normal range.

During July - September 2015, above normal pressures are forecast to the west of New Zealand, with below normal pressures expected well south, and northeast, of the country.

This mixed pressure pattern is likely to be accompanied by anomalous southerly-quarter wind flows, which is typical of El Nino conditions during the winter season in New Zealand.

Sea surface temperatures around the coasts of New Zealand are expected to be near average for the coming three months.

An outlook issued by WeatherWatch.co.nz today reported that July would start off wet in the west, dry in the east, and warmer than average for most places, with plenty of wind from the west, north and east.

"We'd be expecting a return to west to south west winds later in the month, which could help create another polar snap later in the month, or into August," the website reported.

The milder weather would be a welcome change from a dramatic June, which saw heavy snow falling above 300m in Otago and Southland, temperatures below minus 20 reported through the South Island's interior and torrential rain which flooded Dunedin, Hokitika and Wanganui.