Earlier forecasts, confirmed as late as two weeks ago, put the figure between 20mt and 22mt.

But poorer crops in parts of southern NSW, Victoria and South Australia and frost-affected areas of WA have caused a reassessment.

Harvest in Western Australia’s northern wheatbelt is well underway with expectations of an above average season following two very poor harvests.

Rain this week halted programs starting further south and east but those areas are likely to start next week.

All eyes are on the central wheatbelt where estimates of frost-affected crops remain unclear though anecdotal reports from farmers suggests variable crop losses averaging less than 30 per cent.

Overall, the state is poised to record its best harvest since the record 2005 season.

In South Australia, most areas have suffered from reaching yield potential because of a dry Spring.