New Zealanders should expect more extreme conditions this spring and summer as a result of an El Nino weather pattern, says the World Meteorological Organisation.
In its latest update, it says there are rapid changes occurring in the tropical Pacific that will have an impact on the climate throughout the Pacific Basin.
Spokesperson Jim Salinger says the pattern often brings cooler south westerlies in spring and more westerly winds in summer.
Dr Salinger says that means it is likely to be cool and wet in the south of the country, but dry in the north and east, and in the northeast of the South Island.
He says the El Nino pattern is likely to be weak to moderate and will last into first quarter of 2010.