Niwa outlook: La Niña effects may bring drier weather and heatwaves to Manawatū this season

National Institute of Water and Atmospheric Research’s (Niwa) August-October seasonal outlook states there is a 55% chance of temperatures being above average in the central North Island region, which includes Taranaki, Whanganui, Manawatū, Horowhenua and Greater Wellington. Photo / Niwa

Manawatū residents can expect warmer days according to the National Institute of Water and Atmospheric Research’s August-October seasonal outlook.

The Niwa report states there is a 55% chance of temperatures being above average in the central North Island region, which includes Taranaki, Whanganui, Horowhenua and Greater Wellington.

Niwa principal scientist of forecasting and media Chris Brandolino said the expected temperature rise is due to La Niña, the cooling of surface ocean water along the tropical west coast of South America, resulting in humid north easterlies.

The northeasterly winds will contribute to the temperature being above 25c for more days than normal, he said.

“We think there’s a 60 to 70% chance this will develop by December, bringing more high pressure south of New Zealand over the next three months, coming with a gradual reduction in the typical westerly winds. This means drier weather.”

Before it dries off, people can expect an unsettled start to the season.

“People may experience wetter weather but that is not indicative of how the season will go as a whole. This doesn’t mean that every day it will rain, it just means as a whole, the trend is unsettled weather.”

Rainfall has equal chance of being near normal or below normal, according to the Niwa seasonal outlook for October -December. Photo / Niwa

He said that, despite this, the area is expected to have a drier lean with equal chances of rainfall being near normal or below normal.

“We are just reporting on the trends of what we could expect for this upcoming season.”

There is the potential for dryness over November and December, Brandolino said.

“This is from those northeasterlies caused by La Niña. Historically, those heatwaves will create an inviting temperature for swimmers and surfers.”

He said another event that will impact the heat is the ocean temperature.

“We’re currently watching the water temperature and we expect it to be up, meaning it’s hard to get those long and frequent cold snaps. While this means warm weather for us, we have to think about what this will mean for the aquatic life.”