WELLINGTON - New Zealand had its warmest winter on record for a third straight year.

The nationwide average temperature during winter was 9.8 degrees Celsius, 1.4 degrees above the 1981-2010 mean, the National Institute of Water and Atmospheric Research said on Friday (Aug 2) in Wellington.

It was the third consecutive record warmest winter, it said, adding that six of the top 10 have occurred since 2013.

"Winter 2022 was the first winter on record where the temperature anomaly exceeded +1.2°C for all three months of the season," NIWA said.

"Our coastal seas also had their warmest winter on record, with persistent marine heatwave conditions."

Global warming is manifesting as increased rainfall in New Zealand and Australia, with flooding causing havoc in both countries this year.

New Zealand's glaciers are also shrinking as temperatures climb.

NIWA said it was an exceptionally wet winter, with the vast majority of the country observing above or well above normal rainfall.

"A warmer atmosphere due to climate change" is "strongly contributing to New Zealand's temperature trend", it said.

"Because a warmer atmosphere means water will be in its vapour state (which is fuel for rain), it is likely that the extreme rainfall events of winter 2022 were more intense because of climate change." BLOOMBERG