ANZ senior economist Mark Smith says the trade surplus has reached its peak and exports are set to start falling due to lower commodity prices.
Record dairy exports helped the country post its first monthly trade surplus in five months.
Statistics New Zealand says the surplus stood at $338 million in December, the first since July, while imports fell 1.6%.
Exports rose 13% due to higher sales of milk powder, butter and cheese, while imports fell slightly.
On an annual basis, the surplus totalled $1.1 billion.
Mr Smith says the monthly trade surplus was surprisingly strong but that's expected to change as the high dollar affects exports.
He says over the longer term it will act to slow export activity and will have a dampening impact making imports cheaper compared to domestically produced goods.
Mr Smith says it's likely the trade surplus will tail off over the remainder of the year and move into deficits further out.
