Already, temperatures have soared across the country in late November, a pattern likely to continue until March, principal scientist James Renwick said today.
“In November, pretty much all of the country, the South Island and most of the North Island away from the coast, was quite a bit warmer than normal. Over summer, we’re expecting things to be on the warmer side in most places,” he said.
He said the current warm weather pattern – along with another La Nina heatwave in the late 80s – was the strongest in about 50 years.
People could expect temperatures to be several degrees Celsius above normal, taking some regions into the 30s “from time to time”.
While good news for holiday-makers, it was not so good for Northland or Waikato farmers already concerned about dry conditions, he said.
With little rain forecast before Christmas, Northland farmers facing their third consecutive summer drought this week said they would seek support from the government.
El Nino and La Nina are different stages in a cyclical pattern of climate turbulence in the Pacific.
Tropical cyclone activity is likely to be near – or above-normal – through to May and the risk of an ex-tropical cyclone passing close to New Zealand is slightly above average. Normally at least one ex-tropical cyclone passes within 500 kilometres of New Zealand in the cyclone season.
While El Nino usually brings higher rainfall, La Nina brings cooler sea temperatures, high atmospheric pressure and drier air. Strong winds blow moisture away making for cloudless skies and dry conditions in equatorial countries from the International Date Line east to South America.
“The net result for New Zealand is we tend to get high pressures and more settled conditions,” Renwick said.
Some scientists believe that the increased intensity and frequency – now every two to three years – of El Nino and La Nina events in recent decades is due to warmer ocean temperatures resulting from global warming.
“You could say yes, in that temperatures have risen in New Zealand in the last century, so the chances of getting warm conditions have increased… because things are warming up,” Renwick said.
The source article La Nina heatwave sweeps the country was published December 3, 2010 by TVNZ.com .