Autumn outlook: Above-average warmth with remnants of weak La Niña

Whanganui can expect a warmer-than-usual autumn, Earth Sciences NZ says.

A warmer-than-usual autumn is expected for the Whanganui-Manawatū region as the La Niña phase, which set the tone for summer, moves on.

Earth Sciences New Zealand (ESNZ) meteorologist Chris Brandolino said it would result in a “long tail of summer”.

Autumn conditions are expected to be calm, fine and dry.

ESNZ predicted a 50% chance of above-average air temperatures for autumn, with a 40% chance of average temperatures.

Climate conditions are driven by swings in surface temperature and atmospheric pressure, consisting of El Niño (warm), La Niña (cold) and neutral phases.

“A climate driver is basically ... who’s at the steering wheel of Mother Nature’s car?

“That’ll tell you what direction you’re gonna go,” Brandolino said.

A neutral phase was 95% likley to persist until May.

However, the expected above-average temperatures this autumn did not guarantee consistency.

“Even though La Niña is in the rear-view mirror and has ended, the atmosphere has a memory.

“Every now and again, we are expecting these La Niña-like coughs from the atmosphere.”

Significant rain and unsettled conditions could also seep into North Island regions at intervals in March and April.

There is a 40% chance that rainfall will be above average and a 35% chance it will be near average.

Soil moisture and river flows are most likely to be near normal.