Temps do not cool down much.
Sorry, but little do you know about the North,(yukon) Even though we get long daylite hours, the temps do cool off a night. Right now (in Whitehorse) we are getting great summer weather, +26 c this afternoon, but by morning, it will be about +7 or +8c. I get up in the morning and need to put the liner in my jacket, by noon it is too warm.
Enough about that, hope the long distance ride goes good.