The muggy, showery weather is set to continue for the next couple of days after Rotorua experienced its hottest December day on record this week.
The National Institute of Water and Atmospheric Research said the temperature reached 28.4C on Monday to become the warmest December day on record for the town.
Monday's temperature beat the old record of 28.3°C on December 28, 2015 with records going back to 1972.
MetService meteorologist Angus Hines said it was a static weather situation for Rotorua over the next couple days with warm and humid conditions expected.
"There is muggy air near the surface of the atmosphere with cooler air above it. This could produce thunderstorms around the region and potentially small bouts of hail."