Every Thursday evening, Higuera Street closes to traffic from about Osos to Nipomo Street and becomes something between a farmers market, a street fair, and a weekly civic ritual. Restaurants set up BBQ grills on the sidewalk, local farms sell produce and flowers, food stalls run down the middle of the street, and live music plays at several spots simultaneously. The crowd runs from Cal Poly students to local families to retirees who've been coming for decades.
This is generally considered one of the best farmers markets in California, which undersells what it actually is — it's a community event that uses the produce-and-food format as a framework. The vegetables are good, but people come for the atmosphere. Portions from the BBQ stalls are large and cheap; local wine and beer are available at the restaurant stalls. By 8 PM it's shoulder-to-shoulder on a good night.
It runs every week, year-round, including in winter. Rain occasionally thins the crowd but does not cancel it. If you're in SLO on a Thursday, organize your evening around this.