Chicago Board of Trade (CBOT) corn futures fell for a fifth straight session on Wednesday and touched a five-week low on weak demand for US exports and as the US harvest proceeds in mostly dry Midwest weather, traders said.

CBOT December corn closed down 3 cents at $3.78-3/4 per bushel. The contract fell to a low of $3.77-1/2 during the session, the lowest since September 30. Grain traders are adjusting positions ahead of the US Department of Agriculture's (USDA) monthly supply/demand reports on Friday. Analysts polled by Reuters expect a small reduction to the average corn yield despite poor weather this season.

Largely dry US Midwest weather is allowing farmers to continue harvesting corn in much of the region. Below-normal precipitation is expected over the next week.