NZ has fifth-warmest year since 1909

Lake Tekapo, site of the Church of the Good Shepherd, recorded the country's lowest air...
Lake Tekapo, site of the Church of the Good Shepherd, recorded the country's lowest air temperature in 2017: minus 14.6degC. PHOTO: DESTINATION MT COOK MACKENZIE
If you thought last year's weather was warmer, wetter and yet somehow drier than usual in Otago, you were right.

Otago features frequently in Niwa's 2017 New Zealand Climate Summary, after setting weather records.

The summary, which was released yesterday, shows 2017 was the fifth-warmest year on record for New Zealand, based on Niwa's seven-station series, which began in 1909.

It showed the annual average temperature was 13.15degC - more than half a degree above the 1981-2010 annual average.

Leigh, north of Auckland, recorded the nation's highest annual average temperature with 17.0degC, and the highest air temperature was 35.5degC, recorded at Wairoa and Ashburton on February 6.

Otago was singled out in the Niwa statistics on October 19 and 20, when a warm northwest Foehn wind caused temperatures to exceed 30degC in some locations.

Cromwell recorded 28.6degC on October 19 and 30degC on October 20.

The October 20 temperature set a monthly record and was also the warmest Cromwell temperature on record between April and October.

On October 30, another northwest Foehn episode brought warm temperatures to Southland and Otago, and Invercargill recorded its highest October temperature (25.9degC) since records begin in 1905.

On November 23, Cromwell reached 33.3degC, its hottest November and spring temperature since records began in 1949.

In addition, from November 19-30, Cromwell recorded 12 consecutive days with a maximum temperature at or above 25degC - the longest November hot stretch on record.

The wettest place in New Zealand for 2017 was the Cropp River, on the West Coast, which recorded 8662mm of rain for the year. Milford Sound and Franz Joseph were close behind with 6000mm and 3587mm, respectively.

Oamaru featured in the Niwa statistics because its annual rainfall was 813mm (172% above normal) for 2017 - the second-highest annual rainfall since records began in 1941.

``It was notable that Oamaru recorded 161mm of rain on July 21 (the wettest day in the town on record since records began in 1950), but then recorded 163mm during the following five months combined (August-December 2017),'' the Niwa report said.

By contrast, annual rainfall was 50%-79% below normal in much of Southland and interior Otago.

Clyde, which had 278mm of rain last year, is one of the driest places in New Zealand. PHOTO: JONO...
Clyde, which had 278mm of rain last year, is one of the driest places in New Zealand. PHOTO: JONO EDWARDS
The development of La Nina meant very low rainfall during November and December, which led to meteorological drought in 11 of New Zealand's 16 regions by the end of the year.

Otago had seven of the eight driest places in New Zealand for 2017. Clyde was the driest with just 278mm of rain falling in 2017, followed by Cromwell (280mm), Alexandra (297), Ranfurly (344mm), Lauder (347mm) and Wanaka (516mm).

Annual sunshine was mainly near normal (90-109% of the annual normal) or above normal (110-124% of the annual normal) throughout New Zealand.

The wider Nelson region holds the record for New Zealand's highest annual sunshine hours, totalling 2633 hours during 2017.

Balclutha had the second-least sunshine hours in New Zealand, recording just 1655 hours.

University of Otago honorary research fellow Jim Salinger said it was a year of extreme weather events.

The standout events were the North Island floods caused by ex-Cyclone Debbie and ex-Cyclone Cook in April, the eastern South Island floods in July, and the marine heatwave that started in September and peaked in December.

Floods in the first seven months of 2017 meant it was the most expensive year so far, costing $242million in insurance payouts.

``New Zealand is now ranked as high hazard for these events by the Global Facility for Disaster Reduction and Recovery.''

The marine heatwave created temperatures at least 3degC above average for several weeks in the latter part of 2017, which had significant impacts on the marine environment.

``There will be a movement towards more subtropical species of pelagic fish further south,'' Dr Salinger said.

``Already, snapper have been caught during December 2017 in Doubtful Sound, Fiordland, which has never occurred before. And snapper have been spawning three months earlier than normal.

``Many other impacts are likely, such as changes in shellfish and seaweed around the coasts.''

Dr Salinger said the Bureau of Meteorology had forecast the marine heatwave to continue for the rest of the summer, particularly in southern parts of New Zealand.

``The early indications are that 2018 in New Zealand will be warmer than 2017, making it one of the warmest of years for a while.

``The impacts of extreme weather in 2017 give us a taste of things to come in a warming climate,'' he said.

john.lewis@odt.co.nz

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