Days at the beach are numbered, as Kiwis are facing a muggy, wet remainder of the summer.
The month of December was the second hottest on record, and January so far, according to Niwa, looks set to break records.
One climate scientist, Jim Salinger, believes if the average temperature for the month slides up only half a degree, it may be the hottest month since records first began.
The average January temperature is 17.1 degrees centigrade, the average so far for January 2018 was 19.3C - the hottest since records began in 1909.