X2 on what the others have said. Generally speaking October is a great month to be in Colorado. Last year I was up in RMNP at Moraine Park in October. Cold at night, beautifully crisp during the day. Trail Ridge didn't close until the end of the month, although Glacier Basin CG closed in September (as is their custom). Altitude and Latitude are determining factors.
My son's birthday is in late October (the last week) and for years, without fail, it would be beautiful the day before his birthday, and would snow either on or the day after. Go figure !:?