In local currency terms the ANZ World Commodity Price Index (WPI) showed a gain of 3.9%, largely salvaged by a 2.1% fall in the New Zealand dollar trade weighted index for the month.
At 294.5, the WPI index remains off May's high of 309.8.
ANZ agricultural economist Susan Kilsby said the bank was forecasting further downward currency movement in the coming months, supporting export returns to New Zealand producers.
The report showed a month-on-month improvement of 1.3% in dairy prices, which have a 38% weighting on the index, on the back of firmer milk power prices, although butter prices softened.
The forestry price index lifted 0.7% in August following a sharp downward correction in July.
Ms Kilsby said the fall in the in-market price of logs in China earlier in the winter had resulted in a decrease in the quantity of trees being felled in New Zealand as some small woodlot owners elected to leave trees standing.
''Prices are now starting to recover and are expected to continue to lift as building activity picks up.''
Aluminium prices fell 3.1% in August after gaining 2.4% in July, attributed to recent tightening of production in China which pushed up the aluminium price within that market though ''prices elsewhere remain subdued as concerns grow about weakening global conditions.
''Dairy prices are currently bumping along but are yet to show the upward trend that slowing global growth in milk supply suggests is due,'' she said.
Despite continued strength in international lamb prices, the meat and fibre index eased 0.7% during August with less bullish beef prices.
Ms Kilsby said while demand from China remained robust on the back of the swine flu epidemic, prices had nonetheless eased slightly in US dollar terms on the back of the weakening of the yuan.
Coarse wool prices remained under some pressure, the trade war ''not helping,'' she said.
The horticulture index rose slightly on firmer kiwifruit prices, while apple prices softened.
She said shipping costs were firmer in August despite concerns of slowing global trade. Shipping and trade indicator Baltic Dry Index lifted 27% during August to reach its highest level in almost nine years.
''Part of that relates to a reduced supply of ships as owners dock ships to make alterations to meet the tighter environmental regulations from next year.''
