Grand Canyon South Rim, at about 7,000 feet elevation, is generally pleasant in the summer, with the average high temperature 84F and the average low 50F in July (the warmest month). Be prepared for afternoon thunderstorms July thru mid-September, with frequent lightning hazards at rim overlooks (nearby trees are not safe shelter). The bottom of the canyon, at an elevation of 2,500 feet, is prohibitively hot in summer; the average high in August at Phantom Ranch is 106F, and the average low is 76F.
Spring months, April and May, are typically windy, with gusts frequently reaching up to 40 mph. Wear a hat with a chin strap along the canyon rim or you may lose it. Winter and spring months experience snow, sometimes as early as October and as late as May. Primary park roads are plowed; call (928) 638-7888 for winter road conditions. Grand Canyon trails in winter and early spring are often packed with snow and ice; instep traction devices advised. The average daily high at Grand Canyon South Rim in January (the coldest month) is 44F and the average low 14F. Meanwhile, Phantom Ranch in January experiences an average daily high of 57F and a low of 37F.