West in for worst of El Nino rain

In October the El Nino phenomenon makes one side of country wet and the other dry. Photo / NZME

New Zealand will be a divided country, weather-wise, in October as the El Nino phenomenon makes one side wet and the other dry.

After a very cold September, MetService meteorologist Georgina Griffiths said eastern regions of New Zealand should enjoy spring-like temperatures.

October temperatures were predicted to be average, or above average, in the east of both islands. But the west side of the whole country and all of Southland would be wet for much of the month.

The South Island's West Coast would be as damp as usual "but that, to be fair, is fairly wet anyway", Ms Griffiths said. "We haven't yet seen the typical westerly gales that start spring - but that's about to change. We expect more westerly winds than usual over the country during October."

The east-west divide will even affect skinny Northland and the Bay of Islands will likely be much drier than the region's western centres.

Taupo and central mountain ranges, such as the Ruahine and Tararua ranges, would divide the dry east from the wet west. In the south, the Southern Alps and the Catlins further south would act as a similar boundary.

WeatherWatch said temperatures in the South Island will be all "mixed up" as increasing clouds and patchy rain create a volatile situation.

"Next week high pressure dominates north of New Zealand - meaning the winds get stronger the further south you head," WeatherWatch said, adding windy westerlies will return later next week.

The Waikato and Bay of Plenty could expect a mostly sunny day today, as could the East Coast. From Taranaki to the Kapiti Coast, mostly cloudy skies would prevail and the odd shower was possible, WeatherWatch said.