It can snow there then, but nothing to worry about the Park Crew is really good about keeping the roads clear in the High Country. The roads will be plowed before day break! And it can get a little chilly at night! One year the DW and I went there in mid October just spectacular with all the fall colors. It was 70* during the day and very low 30*s at night and it would snow every night. The Buffalo's were dragging there bellies in the snow in the high country but, the roads were bare! We alway's stayed at Mammoth Hot Springs (Nat'l Park Campground) everything we need is there Store, gas, restaurant etc. and we alway's seen more animals in the Northern part of the Park.