Niwa principal scientist for climate Brett Mullan said that, while we continue to pump greenhouse gases into the atmosphere, we will continue to break records.
Mullan said the warmer conditions could be bad news for the horticulture industry, aiding the spread of crop diseases and pests.
But Dairy NZ spokesman Andrew Reid said a hot year was not necessarily a bad thing for dairy farmers, provided it didn't turn into a drought.
"Typically hot conditions are a good thing, because it means good pasture if you have moisture in the soil. If it turns into dry conditions then farmers need to ensure they have a plan in place."
This year it had been unusually wet weather that was affecting production, he said.
New Zealand's average temperature for 2016 is currently sitting at 0.94 degrees Celsius above the 1981-2010 average.
Christchurch was less of a departure from the norm, but still had its hottest year since 1998.
At Niwa's Baring Head Clean Air Station, near Wellington, the levels of carbon dioxide – the primary greenhouse gas contributing to atmospheric warming – also broke records, passing the 400 parts per million (ppm) threshold in June.
Globally, the World Meteorological Organisation said 2016 was set to be the hottest year by a significant margin, with temperatures 1.2C above pre-industrial times.
If confirmed by the year's end, it would mark the third record year in succession.
Temperatures for the rest of the year would have to drop markedly, to more than 1C below normal for the next three weeks, to avoid the record being set.
Mullan said Kiwis would not bear the brunt of the warming, which would fall heaviest on areas that were already very hot, including India and the Middle East.
The first six months of this year were exceptionally warm, which Mullan said was a consequence of the long-term regional warming trend caused by greenhouse gases and local natural variability.
"Natural variability acts like a tailwind or headwind, pushing local temperatures either above or below the long-term trend. In 2016, sea surface temperatures in the Tasman were exceptionally warm and there was more northerly flow than usual over New Zealand, pushing local temperatures above the trend."
National measurements date back to 1909. During this century, only four years have recorded colder-than-average temperatures: 2004, 2006, 2009, and 2012.
This year, August was the only month that dipped below normal.
Mullan said he expected to see the record for the hottest year beaten repeatedly in coming years.
"I don't expect to ever again set a record low temperature. Those have come and gone."