Rains at this time of year can turn milling wheat to feed. About 50% of the harvest in New South Wales may be affected by the rains, said the grain trader from Melbourne.

The main developer of forecasts of Australian commodities in September estimated the production of wheat in New South Wales at the level of 7.2 million tonnes with a total forecast production in Australia at the level of 25.3 million tons.

But the recent dry weather after this forecast means that most traders and analysts expect that production in New South Wales will significantly fall below 6 million tons.

Lowering quality on a large scale will reduce the amount of milling wheat available for shipment in the fourth-largest global exporter by supporting global prices, which fell to five-year lows in September due to sufficient supply.

Leading importers of Australian wheat, including the world's second buyer of Indonesia, may be forced to send more grain from the United States or Canada, if the "grain belt" of Australia will suffer.

The prospect of rain recalled the situation in 2011, when ready to harvest the wheat has suffered from the hurricanes that half of the harvest on the East coast of the country downgraded to feed quality.

The decline of grain quality may also create further problems for grain handlers who receive income from exports.

GrainCorp Ltd, which announced on Tuesday the fall of 2015 income to a seven-year low, warned that grain production on the East coast of the country may fail to achieve official forecasts.

Official forecasts compiled by the Australian commodities reported in September that production of winter crops on the East coast will reach 16.1 million tons, but the management of GrainCorp reported that the forecast will be lowered by dry weather, which lasted the last months, while wet weather this week could also impact on production.