Fonterra has issued its 2015/16 farmgate milk price forecast at $5.25 per kg of milk solids and has cut its forecast for the current season, which ends on Sunday, by 10c to $4.40 a kg.
Analysts had expected the co-operative to pitch its 2015/16 forecast at close to $5.00 and said there was an outside chance the current season's forecast would be reduced.
Along with its previously announced forecast dividend range of 20-30 cents per share, farmers will face a cash payout of $4.60 - $4.70 a kg for the current season.
Fonterra said in a statement its advance payment for the next season would come to 3.66 a kg.
At $4.40, the current seasons' farmgate milk price is the lowest in eight years.
Chairman John Wilson said the downwardly revised forecast reflected the reality that global commodity prices had not increased as expected.
"World markets are over-supplied with dairy commodities after farmers globally increased production in response to the very good prices paid 12-18 months ago," he said in a statement.
"This supply imbalance has heightened due to continuing good growing conditions in most dairy producing regions," he said.