Australia's floods, while causing an estimated $2.5bn in losses, may not have damaged agricultural prospects that much, but the drought which preceded it did, officials said, slashing by 28% their forecast for the sorghum harvest.

The flooding caused last month by the remnants of Tropical Cyclone Oswald left "limited areas affected by floodwaters for up to a week, and in these regions some damage to summer crops was caused by floodwater inundation", Abares, Australia's official crop bureau, said.

But overall, the flooding "has so far caused only minor damage to summer crops", said Paul Morris, the Abares executive director.

Indeed, the heavy rains - which insurer AON Benfield estimated caused $2.5bn losses in Queensland, the main area affected - improved sowing conditions for late-planted summer crops, such as sunflowers.

'Heatwave conditions'

However, the drought, and record temperatures seen until mid-January, did damage harvest prospects for earlier-seeded crops, by causing "widespread deficiencies" in soil moisture.

"The 2012–13 summer crop season has been unfavourable to date for most crops with heatwave conditions in early to mid-January and, until recently, generally very-much-below-average rainfall across the major summer cropping regions," Abares said.

The dryness had hurt in particular prospects for sorghum, in which the bureau ditched expectations of a rise in output this year – forecasting instead a 23% decline, to 1.71m tonnes.

"The drier and warmer conditions in late spring and early summer have resulted in many producers not fully realising their planting intentions for grain sorghum, and reduced yield prospects," Mr Morris said.

Grains upgrades

The dry weather came too late, however, to cause damage to the important winter crops, including wheat, for which Abares nudged its 2012-13 harvest estimate 42,000 tonnes higher to 22.04m tonnes.

Abares left at 20.9m tonnes its forecast for Australian wheat exports during the marketing year.

The estimate of the barley harvest was upgraded by 196,000 tonnes to 7.06m tonnes, and for canola production by 453,000 tonnes to 3.09m tonnes.