Oh, I almost forgot, WIND.
http://forecast.weather.gov/MapClick.php?map.x=154&map.y=163&site=unr&zmx=1&zmy=1
The seven day forecast is a day short for your arrival, but as you may see, wind, snow, cold temps, etc are in the upcoming seven day forecast. This, BTW is one of, if not the coldest Octobers in my 30 year experience in Rapid City.
I’ll be there, too, with a bunch of friends and family. Wish you could have made arrangements to do it at Mt. Rushmore. That would have been awesome! I hope all of you have time to make the trip up to the Monument.
Really looking forward to seeing all of you.