Sorry to drag up old news! But when you sign up for USPS service it asks on your application what you want them to do w/ packages if you aren't at home (leave at door, leave notice, etc) OR I would think that if there isn't some kind of protection from the weather they may not leave it at all. Depends on how kind hearted your carrier is

Sometimes I get packages left here, and if the weather is bad my carrier takes them back to the PO!
Just my $0.02