Tauranga reached an official scorching 29.9C yesterday, making it one of the hottest days on record.
Niwa climate scientist Georgina Griffiths, who was in Tauranga yesterday, said there had been only 21 days warmer than yesterday's maximum, since records began 100 years ago.
"It's a notably warm day," she said.
It was the hottest day this summer, far surpassing the 27.7C recorded on December 19.
"That's a big jump," Mrs Griffiths said.
"The Bay of Plenty often gets 28C but anything over 30C is unusually warm ... it's not surprising people are running for the beach."
The top three temperatures on record for Tauranga were 33.7C in January 1983, 33.3C in 1946 and 32.6C in 1940.
The hottest temperature in the country yesterday - 32.1C - was recorded at Kawerau, followed by 32C at Whakatane.
An unscientific temperature survey, by the Bay of Plenty Times, recorded by a digital weather station, showed a range of different temperatures for the Western Bay of Plenty.
Te Puke bore the brunt of the region's heat, reaching 40C in the town centre according to the device.
"I knew it would be over 30C," local resident Kui Shortcliffe said.
Ms Shortcliffe said the heat was "like Brisbane heat".
"It's crazy hot," she said.
The heat was such that the tar melted on State Highway 2 north of Te Puke and caused chunks of the road to lift off as traffic travelled over the top.
After two minutes inside the Bay of Plenty Times vehicle at Te Puke, the temperature rose to 44C.
At Welcome Bay Shopping Centre 36C was reached.
At Papamoa, the temperature was 38C and the beach experienced one of its busiest days this summer with cars at Papamoa Domain overflowing out of the car park and allowing little elbow room on the beach itself.
Local resident Glen Moran estimated the temperature was about 26C and while surprised at the heat, agreed it was a scorcher day.
At Mount Maunganui and Tauranga's city centre, the temperature was 33C.
Renee Jackson, 27, and Toni Ritchie, 24, escaped the crowds at Mount Maunganui Beach and McLaren Falls by finding a secluded spot on the Wairoa River. The Brookfield friends have been travelling out to the cool, deep, water hole at least twice a week.
"It's too busy at the Mount and the water is nice and fresh," Ms Jackson said.
"I got straight out of bed and came here," Ms Ritchie added.
A warm breeze under the shade of a tree was the only reprieve for a group of carpenters working on the new Tauranga police station in Monmouth St.
"She's hot man. She's a scorcher," one worker said.
"I bring in a full bottle of frozen water and by 10am it's thawed out and it's been sitting Blistering heat hits region's centres
in the shade. You could tip Milo into it and get a warm drink," he laughed.
Bunnings Warehouse at Mount Maunganui has experienced a jump in sales of umbrellas and swimming pools over the past week.
"It's just what happens at this time of year," said service desk representative Jordyn Brierley.
Tay St Dairy owner said the whole week had been exceptionally busy.
"It's been super hot over here ... non-stop ice-creams and drinks for three to four days and milkshakes. It's been crazy, a good crazy," he said.
"It's been fantastic, comparing it with last year. Obviously all the retailers are much happier."
Mrs Griffiths said while hand-held climate devices had a place these were "not very robust".
The official readings from Tauranga Airport were taken with equipment and in a setting that met world meteorological standards, she said.
"It's about comparing apples with apples. Globally there is a standard so you're not comparing the inside of a car with a grassy paddock," she explained.
Urban areas often got "quite warm", she added. "Out of the wind, where there is lots of concrete around, will feel warm."
Met Service forecaster Philippa Murdoch said the maximum today was likely to sit in the mid-20s.
"Basically the warm temperatures over much of the country over the last couple of days have been due to a very warm air mass spreading over the country from Australia. Now it's starting to move away and there is more of a south westerly flow over the country bringing in a bit of slightly cooler air," she said.
A Niwa Seasonal Climate report has shown that Tauranga can expect temperatures, rainfall, soil moisture levels and river flows are all likely to be in the near normal range for January to March .