It's been a similar situation in WA to that of the widespread harvest hold-ups in the eastern states.

Especially in Queensland and NSW, widespread late spring and summer rain, with hail in some areas, has slowed progress with the national grain harvest, also resulting in significant quality downgrades for wheat and barley, at many grain receiving centres across the nation.

Wheat and barley are being downgraded to livestock feed quality, after failing to meet Australia's high standards, required for wheat for Australian milling and for export milling grades.

On December 10 last year, WA CBH reported the harvest was almost complete and on track to be the fastest recorded, with 90pc of harvest wrapped up in only nine weeks.

At that stage, total receivals were 7 million tonnes out of the estimated 8mt crop.

The dry conditions experienced throughout November were giving growers perfect conditions to accelerate through their harvest programs.

But what a difference a year makes in WA.

This year's progress has been stunted by ongoing wet weather, with the rain (and hail in some places) arriving in bucket loads.

During the growing season, the rain has acted without concern for the welfare of WA growers, failing to arrive when needed most and barely a trickle when it eventually did.

Last week's untimely rain is also costing growers millions of dollars in lost marketing opportunities, with most grain prices dropping considerably during the delays.

In particular feed barley has copped a hammering, dropping almost $100/tonne over the past month while malting barley, wheat and canola have gone down slightly.

CBH operations manager Mike Musgrave said wet weather across WA meant only about 30pc of harvest has been completed.

As of early Monday afternoon, Mr Musgrave said only 3.63mt of grain had been received, from an estimated harvest total of 12mt.