Our grain prices take their lead from CBOT also.... because such a  large percentage of Australian grain is exported, rather than for domestic consumption.....
 
And as  mentioned for  Canada,   Exchange Rate  can  play a  significant  role.

But in severe drought years  when  fears of having enough  grain at home start to increase,  then  CBOT  has less direct effect.   
 And then   emotions  take over....... But  isn't that how all markets work  ?.