Originally Posted by BlarneyHammer

Doing the Great Divide southbound puts you in Canada and Montana during June, when it's still cold and rains a lot, and you arrive in New Mexico during late summer, when it's warmer than June and rains a lot.

In your case, you're not going to New Mexico, but the question remains: why not start in Salt Lake earlier, when it's cooler, and arrive in Canada when it's drier and not so cold?