"It has been going on for many decades," Stephen Gillett of the town's Parks and Recreation Committee wrote in an email. "We know it was around in the 1960s, but it could be even earlier."
The picnic is set for 11 a.m. to 3 p.m. at the Town Center at 765 Portola Road, and will include live music, children's activities and, of course, picnic food.
The children's activities will include face painting, a petting zoo, pony rides and a photo booth, Gillett wrote.
Food offerings will include the traditional hamburgers and hot dogs prepared by the Boy Scouts. There will also be food-truck fare from Los Tolucas Mexican restaurant in Sunnyvale and Sam's Chowder Mobile, Gillett wrote.
The 2018 picnic introduced new food choices and activities, and set a record for attendance as a result, he noted.
"We moved the picnic to September last year and we're doing that again this year," he wrote. "This is a result of optimizing for when families are back in town from summer vacations and kids are back to school."
The day will start off with Zotts to Tots, a 2.4-mile family run that will start at the Alpine Inn (Zott's) on Alpine Road at 10 a.m. and end at the picnic site at the Town Center.
Participants can register at portolavalley.net or in person from 9:15 to 9:45 a.m.
The cost to enter is $20 for individuals, $30 for couples and $45 for a family of up to five people; the entry fee includes an event T-shirt.