Corn's limiting factor is really how muddy the field is and how bad you want to tear it up making tracks or ruts. rain doesn't really affect the grain. Snow on the corn leaves can plug and freeze in the separator of your combine so snow is a problem.
Aha .... I didn't know that. Thanks for the education, and info. Hopefully, you'll be able to stay on schedule, and finish up by 4-7 days before Thanksgiving !