The June trade data showed an eighth successive surplus of $247 million. On a seasonally adjusted basis, the June trade balance continued to moderate, falling $34 million from May to $174 million for the month.
Total June exports fell 0.7% in value in seasonally adjusted terms from May. This was largely due to a 4.7% fall in dairy export values. With dairy export volumes actually rising for the month, the dairy export value drop was owing to a price fall of more than 7%.
In other sectors, meat export values rebounded strongly from May, rising nearly 9% in June. Forestry values were largely flat.
BNZ economist Doug Steel said the outlook was for a sharp deterioration in the nation's external accounts.
There were hints of the deterioration in Statistics New Zealand June figures.
While June exports were 5% higher than the same month last year, annual growth was a marked slowdown from the positive double-digit pace seen through each of the first five months of the year.
''We think annual export growth will turn negative during the second half of 2014, as the likes of lower dairy product and log prices filter through the official statistics.''
New Zealand's exports to China also showed a stark contrast between very strong past performance with signs of softness now creeping in, he said.
Reflecting the past year's buoyancy, the value of New Zealand exports rose an ''astounding'' 50%. That was part of the $3.1 billion trade surplus New Zealand had run with China over the past 12 months and a stunning turnaround from the peak $3.8 billion trade deficit back in 2008, Mr Steel said.
But in a clear hint change was under way, New Zealand exports to China for the month of June were 1.5% lower than for the corresponding month a year earlier.
Mr Steel repeated Westpac's long-held view the likes of merchandise trade, terms of trade and current account statistics would all show deterioration in the coming year.
''That forms part of our view the New Zealand dollar is more likely to fall than not in the year ahead.''
It was also the reason why the Reserve Bank increased the intensity of its frustration with the level of the dollar at Thursday's official cash rate announcement, he said.
