Grand Canyon National Park earns our superlative for “best hiking weather” with its reliable sunshine and dry skies. Once the summer monsoon fades in September, October delivers low precipitation, low humidity and an abundance of clear-sky days, statistically one of the driest and most stable stretches of the entire year on the rim. South Rim daytime highs run mild in the 60s, with crisp nights after sunset, making for near-ideal hiking conditions. Best of all, it arrives after the summer vacation crowds have thinned out.