Record temperatures have been set in Wairarapa this summer, with the mercury at times reaching 10C higher than 2011.
Two of the hottest places in the country for Christmas Day were Martinborough and Ngawi, which both reached record-breaking highs.
Martinborough reached a maximum of 31.3C, more than 10C higher than Christmas Day in 2011.
National Institute of Water and Atmospheric Research (Niwa) climate scientist Andrew Tait said Martinborough's weather during the month of December had been hotter than usual.
"The average of all of the December daily maximums was 23.1C, that's 1.7C above what we'd expect," Dr Tait said.
It was also well above December 2011's average of 20.9C.
"So it was quite a warm December," he said.
Ngawi was also 10.5C higher on Christmas Day compared with the previous year, reaching 30C, up from 19.5C in 2011.
The hotter days had brought more swimmers to Martinborough's swimming pool, said lifeguard Issac Sherwood.
"It's been pretty hot the last week or so, it's been around 30C and Christmas Day was pretty hot," he said.
"The last five days there have been about 70 people at the Martinborough pool. You don't usually see that really because it's such a small town, so the heat is really bringing them in."