Corn yields in two major US growing states have come in "at or near record levels", Lanworth said, lifting its estimate for the harvest, and for output of soybeans too.
A survey of elevators in Illinois, the second-ranked corn producing state, and Illinois revealed results of 178 bushels per acre and 174 bushels per acre respectively, historically high levels, the consultancy said.
The average was likely to decline as harvest progresses, with "field observations and expected impacts of extreme conditions during planting and yield formation" indicating that Illinois will end with a figure of 166 bushels per acre, and Indiana with a 170 bushels-per-acre result, Lanworth said.
Nonetheless, the results would be among the "upper scenarios" the group had forecast for the states, and stand above the figure of 165.0 bushels per acre for Illinois and 166.0 bushels per acre for Indiana forecast by the US Department of Agriculture.
'Higher than anticipated'
Indeed, Lanworth, which uses largely satellite data in its forecasts, said that its corn yields estimates "are now higher than USDA's in far western and eastern areas", including Kansas and Ohio.
"Corn vegetation density in these areas," and in some others states such as Minnesota, "remained higher than Lanworth anticipated in the final two to three weeks of grain fill, following the extreme hot and/or dry conditions of late August and early September".
The group raised by 2.5 bushels per acre, to 155.4 bushels per acre, its forecast for the US corn yield, a figure close to the USDA estimate, with the harvest upgraded by 225m bushels to 13.7bn bushels.
The forecast for the soybean yield was also raised, by 0.7 bushels per acre to 41.1 bushels per acre, again close to the USDA figure, with Lanworth attributing its upgrade to "updated image and weather data" for a number of states.
The soybean harvest was upgraded by 44m bushels t 3.6bn bushels.
Dearth of statistics
The data, from a consultancy viewed as one of the more credible commentators, represents among the more methodologically objective data released so far this month, and gives guidance to investors starved of statistics from the US Department of Agriculture, thanks to the government shutdown.
The most serious loss is that of the USDA's monthly Wasde world crop supply and demand report, due on Friday, which had been postponed.
Investors had actually expected the report to raise the USDA yield estimate for corn by 1.0 bushels per acre to 156.5 bushels per acre, and for soybeans by 0.3 bushels per acre to 41.5 bushels per acre.