Your local pharmacist can call for a vacation override and fill the prescription for the time you plan on being away. As others have said, using a nationwide pharmacy like Walmart, CVS or Walgreen can make it pretty easy to get a refill, but there are some hitches with this approach. Technically your prescription is transferred from one store to another and that usually requires the pharmacist at the sending store to be available and handle the transfer. If that person is out for a day or two that can delay the transfer. I ran into this transferring a script between two CVS pharmacies that were less than 10 miles apart from each other. Don't know if it was a legal issue with the State, a CVS policy or just the way things are though.
If it were me (and what I do) is to either work with my pharmacist and get a vacation override or talk to my Doc and get a script for a larger amount covering a longer time period. Sometimes my Doc will give me a script that I can take with me and get filled at a later date when I'm on the road.
And one other thing - don't assume that you can get refills in Canada just because you're using Walmart, CVS, etc. Yeah the stores are there, but Canadian law prevents them from filling prescriptions not issued by a Canadian Doc.