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Fog lifting on the morning of Thursday September 15th, 2011, near the Bright Angel Lodge on the South Rim of Grand Canyon National Park. NPS Photo by Erin Whittaker.

At the Grand Canyon, the heat of summer gives way to a cooler but nonetheless pleasant fall period with average high temperatures gradually falling from the 60s (16-21°C) in September through the 50s (10-15°C) by November along the Rim, and from the 90s (32-37°C) in September to near 70 (21°C) by November along the river. Low temperatures will typically fall below freezing on the Rim, but still remain in the warm 50s and 60s (10-21°C) along the river. The summer rains typically diminish in mid September with a drier fall period the norm with fewer days of precipitation. However, late summer thunderstorms or early winter snow storms have been known to take place during this transition season, making for sudden changes to the weather.