In the summer of 2012, weather conditions caused the most
severe drought the United States has seen since the 1950s.
This drought affected agricultural crops across the nation. As a
result of drought-related crop damage, U.S. export prices for corn
soared nearly 128 percent above the 20-year historical average, as
measured by the Bureau of Labor Statistics (BLS) monthly export
price index. Export prices also hit the highest level since the import
and export price index series began in December 1984
....
Agricultural export prices. Agricultural prices
advanced 12.7 percent in the third quarter of 2012,
primarily as a result of increases in the prices of
soybeans (up 28.5 percent), corn (29.8 percent), and
wheat (29.6 percent). As discussed in the first section
of this report, the severe drought that has affected
much of the nation drove crop prices up. With the
smallest harvest in 9 years, U.S. soybean reserves
hit their lowest level in four decades.19 Despite the
drought in the Midwest, U.S. wheat production was not
affected as much, because most of the wheat in this
region was harvested in the spring and early summer,
before the dry conditions took hold.20 Still, export
wheat prices advanced during the first 2 months of the
quarter, increasing 18.0 percent in July and 9.0 percent
in August, because of a reduction in world wheat
production. Droughts in Russia, Ukraine, and Kazakhstan
cut global wheat stocks for the 2012–2013 season.
http://www.bls.gov/opub/btn/volume-1/pd ... -price.pdf