Mount Rushmore Memorial Day Weekend?
 

I have reservations for 2014 for Mt. Rushmore 3rd week of June. However, due to my daughters scheduling conflict, I am consider rearranging things and just going Memorial Day Weekend. I wonder what the weather would be like there then?

I also wonder what the weather would be like at Cody, Bighorn National Forest, Battle of Little Bighorn Monument. Would I have to worry about roads not being open. I do know that the roads in Yellowstone would still be iffy at that time. Thanks.