Fresno Yosemite International Airport: The most practical flight airport for the south approach. In the summer season, use the YARTS Highway 41 service toward Yosemite Valley rather than renting a car just to fight for Valley parking; allow roughly 3 hours and about $40 round-trip based on recent published fares. Outside its operating season, a rental car via CA-41 is the realistic option: about 1½ hours to the park’s south entrance, then substantially longer to Yosemite Valley.
Merced Regional Airport / Merced Amtrak Station: Merced is the sensible public-transport gateway. Take YARTS on Highway 140 from Merced to Yosemite Valley; allow about 2½–3 hours door to door and roughly $20–30 one way. Amtrak’s San Joaquins/Gold Runner connections meet the Yosemite motorcoach in Merced, making this the best no-car route from the Bay Area, Sacramento, or Bakersfield.
San Francisco International Airport: Choose SFO for flight choice, not proximity. A rental car is generally the least-bad transfer: budget about 4 hours to the park boundary in light traffic, plus the drive into the Valley; Bay bridges and rush hour can make it much longer. Car-free travelers can connect by rail/bus via Merced and then YARTS, but it is an all-day transfer, not a quick airport link.
Sacramento International Airport: A viable rental-car airport, especially from northern California: roughly 4 hours to the park area before the final Valley approach. There is no comparably simple direct airport shuttle; use Merced/YARTS instead if avoiding a car.
Reno–Tahoe International Airport: Useful only when Tioga Pass Road is open, generally around May–October. It is about 3½ hours by car to the Tioga Pass entrance and longer onward to Yosemite Valley. Do not book this routing for a winter Valley trip: Tioga Pass closes with snow.