SAN FRANCISCO - Under grey skies and a steady mist, tens of thousands of San Francisco Giants fans watched their favourite players take photos, wave and mug for the crowd from atop double-decker buses, as the team's victory parade wound through downtown on its way to City Hall.

Young girls with cellphones held high shrieked as shortstop Brandon Crawford rolled by.

"He's the best shortstop in the league," said Jessica Earnshaw, 17.

The San Jose high school senior snapped off several photos of Crawford.

"He's my favourite," she said. "By far."

A broadly smiling pitcher Tim Hudson waved an orange towel over his head to wild cheers. Two buses later, outfielder Hunter Pence, wearing a replica wrestling championship belt and mugging for the crowd, threw his hands up and led several chants of, "Let's go, Giants!"

The parade featured Giants' legends Juan Marichal and Willie Mays. Barry Bonds rode in a convertible, holding an umbrella and smiling broadly.

The fans greeted him loudly and warmly with chants of "Barry! Barry! Barry!"

Sidewalk cannons shot clouds of confetti into the air as a giant panda hovered overhead in honour of third baseman Pablo Sandoval.

Iris Gomez, 37, arrived to the parade route with sandwiches, juice and plenty of rain gear more than 5 1/2 hours before the start of noontime event.

"I love the Giants," she said. "I've been going to the Giants games since the tickets were $8. I wouldn't miss this."

The parade will end at San Francisco City Hall and Civic Center Plaza, where Mayor Ed Lee will honour the team with a giant onstage ceremony.

The 3-2 victory Wednesday against the Kansas City Royals was the Giants' third World Series championship in five years.

Parade efforts were underway long before Sandoval snagged the final fly ball and dropped on his back on the field in victory.

"Unlike most parades where we have weeks and months to plan, this all kind of came down the pipes over the course of days," The Parade Guys' Stephanie Mufson told ABC7 News.

The parade, which is free and open to the public, was a first for 43-year-old Ana Gonzalez, who rose before the sun to drive to San Francisco from her suburban Bay Area home.

With the parade falling on Halloween, it left her and many other parents with a tough choice between celebrating their team and attending school events.

"I asked the kids if they wanted to go to their Halloween parade or the Giants and they said, 'Let's go see the Giants,'" Gonzalez said.

Police Chief Greg Suhr said the number of officers on the streets Friday will be at least 20 per cent higher than usual, with police dogs helping with security.

"We will prepare for any inevitability, but we are hoping for the best," he Suhr. "I wouldn't be surprised if there were 2 million people in San Francisco (for the event) Friday."

News from © The Associated Press, 2014