Mr Adams said that official high is unlikely to be reached this month, but daily highs of 20 or above for the first half of the month was unusual.
As well, he said, the daily low temperatures for the region had not fallen below 12C overnight so far this month, making for a far warmer than normal night time for the month.
"Next week is looking like the temperatures will drop a bit up there. Not by as much as some places further south, where there will be quite a drop, but you'll still notice it being colder," he said.
"But it's likely that even though it will be colder than now, those temperatures will still be a bit above normal for the time of the year."
Mr Adams said temperatures across the country had been higher than normal throughout April and into May, thanks to tropical weather coming from the north.
In April, Whangarei had a mean daily temperature of 17C - above the normal of 16C.