After nearly three years' absence, the El Nino weather system is back, threatening a damp and windy spring.
El Nino - a periodic warming of the tropical Pacific Ocean - affects weather differently around the world and looks likely to land here in September.
National Institute of Water and Atmospheric Research climate scientist Georgina Griffiths said the building El Nino system had stalled this week, but a warm flow spreading across the eastern Pacific suggested it was still on its way.
Cook Strait tended to respond in a localised way to El Nino patterns, which would typically mean a wetter spring along the west of the North Island from Wellington to Auckland.
Coastal Wairarapa and Hawke's Bay would be drier than normal, and temperatures everywhere would be cooler.
MetService's Dan Corbett also expected El Nino to arrive by spring but said atmospheric and ocean conditions still had to unite to create the pattern. "It's like listening to a freight train coming round the mountain - you can hear it but you can't see it."
It was likely to create north and northeasterly winds to Wellington.
El Nino patterns tend to hit by August or September and peak around Christmas.
- © Fairfax NZ News
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