Widespread frost in Western Australia's wheatbelt last month has destroyed more than US$200 million worth of crops, according to the Department of Agriculture.

Cereal crops were severely damaged when temperatures dropped below two degrees across the wheatbelt in late September.

Despite the frost damage which would definitely have a huge impact on output, producers are expected to produce 11 million tonnes of grain, and this year's harvest will be worth about US$3 billion, said David Bowran from the Department.

Meanwhile, global wheat prices continue to fall amid harvesting in the mid-west and wheatbelt. Exporters such as AWB have reduced their estimated pool returns due to the softening international grains market, and APW wheat is expected to sell at US$318 per tonne, down US$41.

Durum grade DRI is the only one to remain steady, with AWB sales forecast at US$440 per tonne.

Wheat prices peaked in February but have been declining due to large supplies from the EU.