It looks likely that the warm temperatures and rainfall the Bay of Plenty experienced during the summer months will flow into autumn.
Niwa forecaster Seth Carrier said Tauranga could expect a warm and wet autumn than usual.
He said the average temperature in Tauranga was likely to be at least 16.2C which was higher than the long-term average autumn temperature for Tauranga which was usually 15.7C.
"We believe that autumn 2018 is very likely to feature above-average temperatures for Bay of Plenty," Carrier said.
Niwa defined above average temperatures to be at least 0.5C warmer than usual and above average rainfall to be at least 120 per cent of normal.
He said the long-term normal autumn rainfall for Tauranga sat at 328mm, but it looked likely that Tauranga could receive 393mm or more this autumn.
The warm and humid forecast for the North Island was linked to lower than normal atmospheric pressure northwest of the country and warm ocean waters.
The good news for farmers was that soil moisture levels and river flows were forecasted to be above normal in parts of the North Island.
"It was certainly both a warm and wet summer in Tauranga," Carrier said.
Tauranga experienced the warmest summer on record with an average temperature of 21C, which was 1.9C warmer than the long-term average, he said.
The warmest temperature was clocked at 29.4C, which occurred on January 24.
Tauranga received a higher than normal rainfall in the summer months at 318mm, when the normal sat at only 259mm.
"That means rainfall this summer was 123 per cent of normal," Carrier said.
Autumn outlook for Bay of Plenty, Northland, Auckland, Waikato
-Temperatures are very likely to be above average (70 per cent chance).
-Rainfall totals are most likely to be in the above normal range (50 per cent chance).
-Soil moisture levels and river flows are most likely to be in the above normal range (50 to 55 per cent chance).