Here’s a tidbit of RVing wisdom that’s been used by experienced travelers going to Alaska. It states that you should be “South of Whitehorse BEFORE Memorial Day and AFTER labor Day.” Granted, you may have to think about that a bit for it to make sense but it simply means don’t plan to be north of Whitehorse before the end of May and make sure you are through Whitehorse (headed south) by the first of September. If you do this, you have an excellent chance of avoiding any late or early snows! You do not want to be driving your RV in snow.
On our most recent trip, we were traveling later in the year than on previous trips—about three-to-four weeks later. We stayed about a week and finally left Whitehorse and headed to the “Lower 48” on Sep. 9th. To verify the above advice, we had one day when the nighttime temperatures dropped to 30° F and we hit some sleet and snow while driving. Luckily, there was not enough to cause us problems but the potential was there.
On the positive side, leaving later and coming down through BC early September, you may see the trees/leaves turning color. Coming back this late, we saw the fall colors in the birch trees. Beautiful!