NIWA reveals New Zealand's wildest weather moments of the 2010 - 2019 decade

The decade is drawing to a close and it's had with its extreme highs and lows - in temperatures, that is.

Meteorologists at NIWA have compiled a list of New Zealand's wildest weather moments of the decade.

Timaru took out the highest temperature with a 41.3C scorcher in February, 2011, while Otago's Tara Hills hit the lowest temperature with -21C in late June of 2015.

Gore might not be everyone's favourite town - but for one day, the sun shone on it and it shone for 15 hours straight; making it the winner of the sunniest single day of the last decade.

But when it wasn't sunny in Southland, it was often cold or gloomy. Takahe Valley had the lowest average of daily temperatures.

Elsewhere, the temperature trend has been up. Five of the past 10 years have ranked among the top 10 warmest years on record.

Victoria University's weather and climate researcher, Professor James Renwick, says there's only one reason for it.

"The globe's warming up. New Zealand's warmed at about the same rate as the rest of the world over the last century," he says.

"That's just consistent with global warming [and] climate change."

The hottest day in the past 10 years was in Timaru on Waitangi Day in 2011. At 41C, it was New Zealand's fourth-highest temperature on record. Professor Renwick says that was to be expected.

But a low of -21C in Otago's Tara Hills in June 2015 caught him by surprise.

"It becomes easier and easier to set high-temperature records and harder and harder to set low-temperature records," he says.

"Those sorts of extremes are going to become rarer and rarer within a few years, I imagine."

Whangarei enjoyed the highest average of hot days, with over 3500 days of at least 20C.

The locals reckon the region is Aotearoa's best-kept secret.

"This is why I moved progressively up north," one person told Newshub.

But Prof Renwick says warmer-than-usual days are a bad sign and he has a strong message for climate change deniers who continue to flood his inbox.

"Natural cycles don't explain what's going on," he says.

"We need to get on and deal with the problem or we're going to be in real trouble."

The professor says if we don't take action, we'll be having more record hot days - and years - in the next decade.