I think this would work if the primary site doesn't yield a result. You can also use Canadian zip (postal) codes, but since canadian codes contain letters and numbers, I can't think of an easy way of inputting them via dtmf
There is one problem, this API is unofficial and Google may remove or change it at any time.
Less detail than the current national weather service, but the Google weather API works with zip codes and looks very parsable.
Usage:
http://www.google.com/ig/api?weather=<zipcode>
I think this would work if the primary site doesn't yield a result. You can also use Canadian zip (postal) codes, but since canadian codes contain letters and numbers, I can't think of an easy way of inputting them via dtmf
There is one problem, this API is unofficial and Google may remove or change it at any time.