El Nino puffs up for a big blow

Climate scientists are re-thinking their outlook for the summer as the El Nino weather pattern strengthens and threatens to bring windier weather to our shores.

This year's El Nino has ramped up during spring, with water temperatures in some regions of the tropical Pacific Ocean up to 6 degrees C above normal.

Armed with this new data, climate scientists at the National Institute of Water and Atmospheric Research (Niwa) will this week begin reviewing their climate outlook for the next couple of months.

They had thought El Nino would have only a minor impact on New Zealand's weather because it had started out as a weak phenomenon, but it is picking up steam.

In El Nino years, New Zealand tends to experience stronger or more frequent winds from the west in summer, leading to drought in east coast areas and more rain in the west. In winter, the winds tend to be more from the south, bringing colder conditions. In spring and autumn, southwesterlies tend to be stronger or more frequent.

Climate scientists in Australia are warning this year's El Nino could now turn into a significant event and lead to drier than normal conditions in eastern parts of Australia. Last week eastern Australia was in the grip of a fearsome heatwave. Firefighters were battling bushfires in four states, with temperatures reaching 42 degrees C in Adelaide, 37 degrees C in Canberra, and 34 degrees C in Melbourne.

Australia's Bureau of Meteorology says the central Pacific has heated up to a level not observed since the El Nino of 2002. On average, water surface temperatures near the Equator are 2 degrees C above normal, but the temperature of some waters deeper down are 6 degrees C higher than usual.