Looking at data from December NIWA's Island Climate Update found that sea surface temperatures have remained above normal for the fourth consecutive month.
Average subsurface temperatures are also above normal.
But the forecasters say while these are two pre-conditions for El Nino weather conditions, almost all of the atmospheric indicators are under the conventional El Nino thresholds.
The El Niño/Southern Oscillation, to give its proper title, is a natural event that involves fluctuating ocean surface temperatures in the Pacific, which influences weather all over the world.
The 2015-16 El Niño was one of the strongest ever recorded, and had an impact on global temperatures, which saw 2016 enter the record books as the warmest year.