Whanganui recorded its third-warmest May since 1937 in a month which included a record-breaking day of rain.

National Institute of Water and Atmospheric Research meteorologist Seth Carrier said Whanganui’s May was “very warm”.

And May 20 was the wettest day ever recorded for the month.

“Whanganui had 62mm of rain that day and a notable flooding event.”

Carrier said May was 2C warmer than normal nationwide.

“This is an extreme anomaly that’s only been seen a few times before.

“Both the month of May and the entire season of autumn were warm and wet for Whanganui.”

On May 1 the daily maximum air temperature was 24.7C, the highest May temperature recorded since 1937.

Carrier said the whole country had experienced very warm weather in the past few months, with New Zealand recording its warmest May ever.

“Through the next decades, the temperature baseline will continue gradually increasing due to climate change.”

Autumn temperatures were above average or well above average across nearly all of New Zealand.

“The nationwide average temperature for autumn 2023 was 14.5C.”

He said there was still going to be variation and not every month and season would set a new temperature record.

But Carrier said people could expect “both sides of the coin” when it came to future weather patterns.

“With climate change when we get wetter weather it can set more rainfall records because a warmer atmosphere can hold more water vapour, and then when there are drier periods those droughts can be more extreme.

“We can expect extremes on both sides.”