"The deals are incredible, probably the best I've seen the day after Christmas, 70 percent off most places," shopper Molly Johnsey said.
Johnsey was among shoppers who got up before dawn to line up for the big sales.
Some go to shop for next Christmas.
"It's worth getting up this early because for next year, you have all the wrap, all the ribbons and stuff for next year, so that's why I come out," shopper Tina Bartunek said.
Retailers have come to expect the flood of shoppers. Many go to return gifts, but that doesn't mean they'll leave empty handed.
"Even if someone's coming into make a return, they want to you know get some more dollars out of their pocket book," Westfield San Francisco Centre spokesperson Amy Benson said.
For some, it's become a competitive sport.
"I got some shoes that would be about $80, but I got them for like $35," shopper Paradise Austin said.
For others, it's a tradition.
"We've been doing this for 30 years; the day after Christmas we come to San Francisco and shop," shopper Judy Speed said.
Retail managers tell us though Monday really is the big day, they're expecting heavy traffic all week. But the smart shoppers say it's right now or never because by the end of the week there might not be anything left.