Scorcher! Tauranga's hottest January in more than 100 years

Crowds of holidaymakers swarmed Mount Maunganui beach in January as temperatures soared. Photo / Alan Gibson

Tauranga has had one of the hottest Januaries in more than 100 years.

A Niwa monthly climate summary released yesterday showed January was New Zealand's hottest month on record and temperatures were well above average throughout the country.

In Tauranga, the mean air temperature for the month was 22.1C which was 2.6C higher than normal. The temperature is the highest for a January since 1913.

Te Puke also experienced a record-breaking January. The Western Bay of Plenty town recorded a mean air temperature of 21.2C, which was 2.9C above normal. It was the highest temperature since 1973.

Western Bay of Plenty District Council Te Puke ward representative John Scrimgeour was not surprised.

"It really just confirms what most of us have been observing. It's been blimmin' hot," the dairy farmer said.

"It's fair to say the heat has been exacerbated a bit because of a lot of northerly airflow which has made it quite humid. It's been uncomfortable for people but livestock too."

Scrimgeour said January had felt hotter than usual but there had been a few cloudy days also which helped.

The summary also showed Tauranga was the wettest of the nation's six main centres. Auckland was the warmest, Dunedin the sunniest, driest and coldest and Hamilton the least sunny. The Bay of Plenty region also experienced above normal soil moisture levels.

Niwa climate scientist Gregor Macara said January had been characterised by higher than normal sea level pressure to the east of New Zealand and lower than normal sea level pressure to the west of the country, resulting in northerly quarter winds. Sea surface temperatures were also up and the combination of this and the winds resulted in higher air temperatures.

The nationwide average in January was 20.3C - the hottest month on record. The previous hottest January was 19C in 1956.

Because the winds delivered a steady stream of humid air, this combined with strong daytime heat helped create short and intense rainfall events.

Niwa forecaster Chris Brandolino said there were a few reasons for January's warmer conditions including warm winds and ocean temperatures as well as climate change.

"One, we had winds coming from a warm place – a lot of northerly quarterly winds," Brandolino said.

"We also had warm ocean temperatures, warmer than average," he said.

Brandolino said those two things, mixed with the fact the earth was warming due to climate change, it was no surprise Tauranga was warmer than normal in January.

"In the background, the temperatures are gradually, slowly increasing. You get those kinds of results.

"If these same conditions replicated in 30 years it will be even warmer because the earth itself will be warmer."

Brandolino said although the first half of February would be unsettled, the second half would likely see warmer temperatures.

"I think you'd find warmer than average temps for the three-month period [of summer], temperatures will be warmer to end summer and begin autumn."

How Tauranga compared, mean air temperature

Tauranga - 22.1C

Auckland (Western Springs) - 22.2C

Rotorua - 20.1C

Hamilton - 21.4C

Wellington (Airport) - 20.9C

Christchurch - 19.9C

Source - Niwa