The festival, held at Squamish's Logger Sports Grounds and Centennial Fields, runs from Aug. 6-9, but heavy traffic is expected from Aug. 5-10, the province said in a release.
"Drivers can expect an increase in traffic volumes and should allow extra time when travelling along the Sea-to-Sky Highway," the release states.
The festival, in its sixth year, does offer paid camping on-site, but there are only about 5,000 camping spots for the estimated crowds of 125,000 people. Last year, 14,460 festival-goers camped.
There are about 6,000 parking spots within walking distance of the festival grounds, but organizers encourage attendees to take a $40 shuttle from Vancouver or Whistler.
"We think shuttles are the way to go," the festival website states. "The luxury, air-conditioned coaches are the easiest, no-fuss way to get to and from Squamish."
MAP: Squamish Valley Music Festival