A new national temperature record of 25.7˚C for June occurred in Hastings, Hawke's Bay, on Monday.
It also qualified as a new North Island temperature record for the winter season of June-August. This is based on NIWA’s climate database, with records dating back to the 1850s.
NIWA meteorologist Ben Noll said there were several factors behind the record-breaking warmth.
“We’ve seen an unseasonably warm air mass over New Zealand that originated in the Coral Sea. This combined with something called a foehn northwesterly air flow, which came over the North Island and warmed as it descended the terrain of the Central Plateau and blew into Hawke's Bay.
“We also can’t ignore climate change - setting a new national temperature record for June is consistent with Aotearoa's long-term warming trend, where we’re seeing fewer cold extremes and more warm extremes,” said Ben.
Temperatures on Monday reached above 20˚C for several regions, including Gisborne, Northland, and other parts of Hawke’s Bay. Conversely, maximum temperatures in the South Island struggled to get above 10˚C in places like Christchurch and Queenstown.
Previously, the highest June temperature ever recorded was 25.4˚C on 19th June 1988, also in Hastings.