Niwa National Climate Centre forecasting principal scientist Chris Brandolino said the La Nina Watch remained active, but the event was less advanced compared to this time last year.
‘‘The short-term influence on New Zealand’s climate likely won’t be as substantial, but is expected to grow over the next three months.’’
He said high-pressure systems were expected to become more common on the east of the South Island, which might increase the chance for dry spells.
It was also expected to be associated with mixed northeasterly and westerly wind flow anomalies.
Over the next three months (October to December), temperatures were very likely to be above average across Otago and Southland, and rainfall was equally likely to be near normal or below normal, he said.
‘‘The first half of October, however, is expected to be unsettled, with periods of rain and possible thunderstorms.’’
He said soil moisture levels were most likely to be below normal in the west of the South Island, and about equally likely to be near normal or below normal in all other regions.
‘‘Soil moisture levels are currently near normal and wetter than this time last year.
‘‘The prevalence of rain-bearing weather systems during the first half of October will likely maintain these conditions.’’
River flows were most likely to be below normal in the west and east of the South Island, and about equally likely to be near normal or below normal in all other regions.
‘‘The development of La Nina-like patterns may contribute to drier patterns in the coming months around the hydro lake areas.’’
He said New Zealand’s coastal sea surface temperatures (SSTs) were 0.4degC to 1degC above average during September, and they were predicted to become ‘‘more unusually warm’’ by November and December.
