"So in short it has generally been warmer than average," Ferris said, "especially in the mornings, with overnight temps 8C to 10C above average."
May has also been much drier than usual, Ferris said.
Rotorua usually averages about 150mm of rain in May. During the first 10 days this month, there has been just 9.2mm.
Tauranga also averages about 150mm of rain in May but has had just 3.8mm in the first 10 days.
Whakatāne averages about 110mm and in the first 10 days had 6.8mm.
"So it's very much drier than the usual average," Ferris said.
However, colder, wetter weather is on the horizon.
"The cold change is on its way, currently zipping up the South Island. It isn't due into Bay of Plenty until Wednesday afternoon," he said.
"This drops the temperature to below-average through into the weekend. This brings wet weather which is semi-persistent on Wednesday, clears throughout Thursday but more is on the way over the weekend.
"Things look to run drier than average next week with temperatures about normal."