Fonterra is expected to downgrade its $7.00/kg milk price when it updates the forecast over the next few days.
The co-op, under its DIRA legislation, has to update its milk price every three months.
The last forecast for 2018/19 was issued late in May.
"Based on results since they opened at $7.00/kg, a downgrade is largely a done deal," ASB senior rural economist Nathan Penny said.
"The debate is around to what number Fonterra moves – a market consensus has formed at around $6.40 to $6.50 kg," he said.