The remainder of spring could be wet for some parts of the country, according to Niwa.
Rainfall could be heavier than normal in the north and west of the North Island, and in Nelson-Marlborough during the next three months, the agency says.
For the rest of the country Niwa expected near-normal rainfall levels.
Air temperatures were likely to be near average or above average in all regions, while sea surface temperatures were expected to be warmer than normal around the South Island, and cooler than normal to the east and north of the North Island.
Thresholds in the Pacific Ocean were close to those associated with the El Nino weather pattern, but New Zealand was not expected to get the enhanced southwesterly and westerly airflow usually associated with El Nino events.
From October to December higher-than-normal pressures were expected south of Australia and New Zealand, with lower pressures forecast to the north of the North Island, Niwa said. That would result in a weaker than normal westerly flow over the country.
- Fairfax Media
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