Be warned — summer traffic is brutal.
The only “safe” time to drive is before 10 am. The park offers limited free shuttle service, including shuttles between the Valley and popular locations like Glacier Point, which can be used to do one-way hikes.
Overall, the main reason to come to Yosemite in the busiest season is for an activity that can only be planned in advance for the warmest months. And of course, if its really the only time you can come, you should still experience Yosemite. Otherwise, we highly recommended checking out our top two favorite months — October and May.
Pros:
Rain unlikely, access to Tuolumne Meadows and the entire high country, full visitor services available throughout the park, Half Dome Cables are up, Tioga Pass open offering access to the eastside including Bishop, Mt Whitney, Lake Tahoe, and Reno.
Cons:
Extremely high visitation; no difference between weekends and weekdays — every day is jammed packed with people. By late summer, waterfalls slow to a trickle or dry up completely. Bad traffic jams and long waits at entrance stations. Holidays are the worst.