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Castlepoint broke three of its temperature records in May, and climate change is partly to blame.
Niwa said Castlepoint’s mean air temperature for May was 16.2 degrees Celsius, 3.5C warmer than normal.
“This meant the mean temperature there was closer to that expected in December, 16.4 degrees Celsius compared to May, 12.7 degrees Celsius.”
Castlepoint’s mean minimum air temperature also knocked records at 13.1C, 3.1C higher than normal.
The beach town also recorded 23.7C high on May 3, the third highest May day in the nation this year.
All three broken records were the highest temperature for Castlepoint since data was first collected in 1972.
A Niwa climate change and variability report produced in 2021 said inland Wairarapa experienced from 30 and 40 hot days a year while coastal areas had from 10 to 30 hot days a year.
It said hot days were days with temperatures of more than 25C.
Niwa said with climate change, both inland and coastal areas could expect to have five more hot days a year by 2040, and up to 70 more hot days by 2090 if emissions were left completely unchecked.
At its most extreme range, inland Wairarapa could spend about 30 per cent of the year with temperatures above 25C compared with an average of 9.6 per cent of the year seen to date.
Coastal Wairarapa could have up to 27 per cent of the year spent with temperatures above 25 degrees.
Castlepoint’s record-high came after a raft of higher-than-usual temperatures across New Zealand this autumn.
National Institute for Water and Atmospheric Research [Niwa] said in its May climate summary that the very warm air temperatures were a result of climate change, more frequent northerly airflows, and ongoing warmer-than-normal sea surface temperatures.
Niwa said the second half of the month had more unsettled weather as several intense low-pressure systems and associated cold fronts crossed the nation.
“These systems brought powerful winds, areas of heavy rain, and numerous thunderstorms – one of which produced a possible tornado in Levin that caused considerable damage to many structures.
Although Wairarapa’s weather was unsettled last month, rainfall stayed below normal in Wairarapa while soils were drier than usual in the south of the region.
Wairarapa stayed off the record mean air temperatures list for May 2021, as well as the mean maximum air temperature and the record mean minimum air temperatures lists
For the second year in a row, Wairarapa avoided being involved in a May extreme weather event.
Niwa’s most latest hotspot watch for May 20 said Wairarapa’s soil moisture ranged from 20mm wetter than usual in the north of the region, and 30mm drier than usual to the south of the region.
As of May 17, Wairarapa was not in a drought according to the New Zealand Drought Index produced by Niwa.
