SAN FRANCISCO — Halloween lands on a Saturday this year, and the Bay Area is treating that as permission to stretch it into a week. From the Fillmore to Fruitvale, there are trick-or-treat trails, night markets, costume parades and block parties, and most of them won’t cost you a thing.

Here is where to take the kids, where to go without them, and a few Día de los Muertos celebrations to carry you into November. Plans change, so check with organizers before you go.

San Francisco

Fillmore After Dark: Halloween Night Market and Kids Scream Zone
The best block party in the city on Halloween night. Live entertainment, spooky bounce houses, trunk-or-treating, a costume contest, classic cars and a food and merchant bazaar, plus a walking tour of Fillmore businesses. RSVP online.
Saturday, Oct. 31, 4-9 p.m. · Fillmore Street at O’Farrell Street · Free

Alamo Scare: Trick-or-Treat the Painted Ladies
The neighbors on Steiner Street turn the most photographed row of houses in America into a trick-or-treat route.
Sunday, Oct. 25, 4-6 p.m. · Steiner Street between Hayes and Grove · Free

Family Halloween Day at the Randall Museum
The city’s hilltop museum throws its yearly family Halloween, with free and low-cost activities.
Saturday, Oct. 24, 10 a.m.-2 p.m. · Randall Museum, 199 Museum Way · Free admission

Magnetic Spinning Spider Workshop at Bayview Library
A drop-in Halloween craft for kids 8 to 13. They’ll work with a hot glue gun, so it’s a good one for the older kids.
Tuesday, Oct. 27, 3:30-5 p.m. · Bayview Library · Free

Hayes Valley Trick-or-Treat Trail and Outdoor Movie
Kids follow the ghost window clings from shop to shop from 4 to 6 p.m., then everyone settles in for a free screening of “Minions & Monsters” at PROXY at 7:30. Grown-ups get a 21-and-over zone.
Friday, Oct. 30, 4-10 p.m. · Hayes and Laguna streets · Free

The Haunt at YBCA
Artists build a Halloween hangout at Yerba Buena Center for the Arts. Evenings are for teens and up; the Friday early show is for families and includes a free headwear workshop by SCRAP.
Oct. 29-31 (family show Friday, Oct. 30, 5-7 p.m.) · YBCA, 701 Mission St. · $25, $15 members, 12 and under free

SuperNatural at the California Academy of Sciences
The Academy’s after-hours Halloween party for families. Adults have to come with a kid; that’s the rule.
Saturday, Oct. 24, 6:30-9 p.m. · 55 Music Concourse Drive · $60 adults, $45 ages 3-17, 2 and under free

Chinatown Halloween Festival
Twelve years running, Waverly Place fills up with families in costume.
Saturday, Oct. 31, 11 a.m.-3 p.m. · Waverly Place between Sacramento and Washington · Free

Halloween Hoopla
Circus Bella performers, live music and a costume parade, built for kids under 10 and whoever brought them.
Saturday, Oct. 31, noon-3 p.m. · Yerba Buena Gardens Children’s Garden, Howard Street between Third and Fourth · Free

Boo at the Zoo
One day of Halloween at the San Francisco Zoo. The activities are free once you’re through the gate.
Saturday, Oct. 31, 10 a.m.-3 p.m. · San Francisco Zoo, Sloat Boulevard at the Great Highway · Included with admission

Oakland and the East Bay

Halloween Land in Richmond
Urban Tilth, the Richmond farm-and-food group, throws a free family Halloween party on the Greenway.
Saturday, Oct. 24, 10 a.m.-1 p.m. · Unity Park, 16th Street and Ohio Avenue, Richmond · Free

Tricks, Treats and Traditions in the Laurel
Trick-or-treat along MacArthur Boulevard from 35th Avenue to High Street, with Día de los Muertos crafts, a community altar, face painting and a DJ. Free treat bags while they last.
Saturday, Oct. 24, noon-3 p.m. · Starts at Golondrinas Mexican Grill, 4171 MacArthur Blvd. · Free

Halloween Pumpkin Festival at Mountain View Cemetery
Eighteen years in, still the best free pumpkin in Oakland — one per child — plus jumpers, face painting, a live animal show and food trucks. Kids under 10 need a grown-up.
Saturday, Oct. 24, noon-3 p.m. · 5000 Piedmont Ave. · Free admission

Lakeshore Halloween Parade and Harvest Festival
A morning costume parade down Lakeshore Avenue, then games, prizes and lunch at Lakeshore Baptist Church.
Saturday, Oct. 24, 10 a.m.-noon · Lakeshore Avenue and Lake Park Avenue · Free

Rockridge Halloween Parade
The 34th year. More than 40 College Avenue businesses hand out candy, with crafts, music, story time and costume contests for kids and dogs.
Sunday, Oct. 25, 11 a.m.-2 p.m. · College Avenue between Broadway and Alcatraz · Free

Boo at the Zoo at Oakland Zoo
Halloween every weekend in East Oakland, with costume contests at noon on Saturdays.
Saturdays and Sundays through Nov. 1 · 9777 Golf Links Road · Included with admission

Trunk or Treat at the Lake
The city parks department hosts a midday trunk-or-treat for the littlest ones, 5 and under, though everyone is welcome.
Friday, Oct. 30, 11 a.m.-2 p.m. · Edoff Memorial Bandstand, Lake Merritt, 664 Bellevue Ave. · Free

Oakland Chinatown Trick-or-Treat Trail
From the Chinatown Chamber of Commerce and the Oakland Asian Cultural Center, with a costume contest at 3:30.
Friday, Oct. 30, 2-4 p.m. · Oakland Asian Cultural Center, 388 Ninth St., Suite 290 · Free

Halloween Jam: Mad Magic at Children’s Fairyland
All-day Halloween for little kids at the park that inspired Disneyland.
Saturday, Oct. 31, noon-7 p.m. · Children’s Fairyland, 699 Bellevue Ave. · $28, free for members

Into November: Día de los Muertos

Día de los Muertos Festival in Fruitvale
The Unity Council’s 31st festival, one of the biggest in the region.
Sunday, Nov. 1, 10 a.m.-5 p.m. · Fruitvale Village, International Boulevard and Fruitvale Avenue · Free

Día de los Muertos Family Fun Fest at Jack London Square
A free afternoon on the waterfront for families.
Sunday, Nov. 1, 1-3 p.m. · Plaza near Scott’s Seafood, 70 Washington St. · Free

Día de Muertos Fiesta at Temescal Brewing
Cumbia DJs, ofrendas by La Familia Quíroz and food vendors. All ages.
Sunday, Nov. 1, noon-9 p.m. · Temescal Brewing, 4115 Telegraph Ave. · Free

Getting home: as of Oct. 19, neither Muni nor BART had announced extra Halloween service, so check sfmta.com and bart.gov before you count on a late train. And when the party’s over, set your clocks back — daylight saving time ends at 2 a.m. Sunday, Nov. 1.