New Zealand had its hottest summer on record in 2018

Tuesday, 8 January 2019

The national average temperature for New Zealand in 2018 made it the second warmest year on record, Niwa has announced.

Last year's average temperature was equal to that of 1998 and second only to 2016, which still holds the record for the highest temperature.

That meant four of the past six years were among New Zealand's warmest.

Aucklanders lapped up the summer sun in Mission Bay during the Christmas break.

However, there were several record-breaking moments. January kicked off the year with the hottest-since-records-began month that later contributed to the hottest summer.

* It was officially New Zealand's hottest summer on record

* Extreme January: Our most sweltering month on record**

Sea surface temperatures around NZ endured a 'marine heatwave' in the spring and summer of 2017-18.

Principal scientist Chris Brandolino gave the details at the Annual Climate Summary announcement in Auckland on Tuesday.

The year 2018 was part of an 'alarming' warmer trend, he said.

Extreme weather events, while already common, are also likely to increase as average temperatures continue to increase.

Climate extremes throughout New Zealand for 2018.

'A changing climate is creating a long-term tail wind for higher temperatures,' Brandolino said.

'January was [the] warmest month, of any year on record,' he said.

NIWA principal scientist Chris Brandolino says January in 2018 was the warmest month on record.

'Six months of the year saw temperatures above average, with no months [with] below average temperatures.'

The mean temperature of 2018 was 13.41 degrees Celsius, 0.8C above the long-term average. Individual climate stations experienced record or nearing-record average temperatures.

The record warmth can be attributed to three factors: Rising ocean temperature, air flow and an increase in greenhouse gases.

A 'marine heatwave' was used to describe the sea surface temperatures, which were above average beginning in November 2017 and persisting until February 2018.

Ocean temperatures affect air temperature, which was a big contributor to the warm year also.

Rain events was described as 'lumpy' switching from wet, to dry, to wet again throughout the year.

However, rainfall was above normal levels across much of the east and upper South Island, as well as in parts of Wellington, Wairarapa, Bay of Plenty, northern Waikato and Auckland.

The sunniest place in New Zealand, for the second time was the wider Nelson region.

A total of 2555 hours of sunshine during 2018 crowned it the 'sunshine king', Brandolino said.

Looking ahead, January 2019 is off to a warm start but record-breakers are hard to beat and it is unlikely to be hotter than last year, Bandolino said.

However, 2019's summer should see the North Island reach above-average temperatures.

'We feel colder-than-usual weather is not likely to define summer,' he said.

'Near-normal rainfall is expected for the next few months.'

An earlier version of this story incorrectly stated New Zealand's mean average temperature in 2018 was 8 degrees Celsius above the long-term average. The correct figure was 0.8C.