Similarly, in Te Puke, record levels of rain fell.
Last month the township received more than 400mm of rain, making it the wettest December since records began in 1973.
The wettest day in Te Puke was December 30, where 98mm of rain fell.
In Tauranga, the wettest day of the month was December 31 where 62.6mm of rain fell in a 24-hour period.
Heavy rain in Tauranga and across the country last month caused the cancellation of many planned New Year celebrations, including those at Mount Maunganui, Palmerston North and Wellington. The weather also caused slips to close two state highways in the region.
While there wasn't much to celebrate, the Niwa report said Tauranga was one of the warmest regions last month.
In December Tauranga basked under 165 hours of sunshine with a mean temperature of 18.2C measured at Tauranga Airport.
This was well above the national average of 15.8C.
However the number of sunshine hours recorded in Tauranga - 165 - was well below normal for that time of year, Niwa said.
Auckland shared the title of the warmest region, the average temperature was also 18.2C, but the region recorded 33 less sunshine hours than the Western Bay.
Of the six main centres in December 2011, Auckland and Tauranga were equal-warmest, Dunedin the sunniest and driest, and Tauranga the wettest.