5 things to do this weekend, from a river festival to Father's Day at the zoo

Ah, June. The ascent to summer solstice on the 21st is my favorite time of the year. We New Englanders have fully emerged from our cold-weather cocoons, and shedding those layers makes it feel like most anything is possible. As the days lengthen, my fantasies of finding fun in the sun abound. And — lucky for us — metro Boston is exploding with myriad ways to come together with family and friends in the great outdoors. Selecting just five things to do this weekend wasn’t easy, but most of them involve spending some QT outside. All could be a lot of fun with dads on Father’s Day, which is Sunday.

The banks of the Charles River transform into a family-friendly outdoor jamboree on Saturday. The Cambridge Arts River Festival's music, theater, dance and poetry will unfold on six stages along Memorial Drive. Also on deck: interactive art-making, buskers, international foods, and an arts and crafts market. The fest kicks off with its famous “Mermaid Promenade” that invites all to dress up as real or imaginary sea creatures. If you — and any dads in your life — are game, line up in Winthrop Park at Winthrop Street and JFK Street by 11:15 a.m.

There’s a dad joke in here somewhere, but Zoo New England is inviting fathers to stop by Stoneham so they can say hi to a two-toed sloth dad named Nero (mom's name is Lunesta). Their seventh little baby sloth was born at Stone Zoo in March. Boston’s Franklin Park Zoo is home to other animal dads, including a western lowland gorilla named Kit, and Chad, a Masai giraffe. Admission at both zoos is free for all on Father’s Day, but advance registration is required. You can reserve up to five spots.

Grab your tote bags and baskets! Most Massachusetts farmers markets revive their selling seasons in early June, including Copley Square's on Fridays, Roslindale's on Saturdays, and the Haymarket in the North End, which is open Fridays and Saturdays. In Harvard Square, you’ll find the Charles River farmers market — also on Saturday — and a few miles away there's Union Square’s enticing bonanza. Need help finding a farmers market near you? Here’s a list, courtesy of the City of Boston. And there’s also this handy map of markets across the state.

More than 300 bands and artists will take over porches, stoops and lawns at the Arlington Porch Fest. The city-wide palooza's genres span everything from Americana to zydeco. WBUR’s own senior producer/reporter and vocalist Lynn Jolicoeur will be crooning along with guitarist George Hicks (a former colleague) in his backyard at 7-9 Bowdoin Street. The annual event’s finale is a family-friendly pop-up dance party dubbed, “Garage Band” at Abe Salhi’s Arlington Service Station (344 Mass Ave at Wyman Terrace). A new arts collective, Mystic Open Studio, will also offer arts and crafts for all ages with help from the Arlington Commission for Arts and Culture. (The rain date is Sunday, June 16.)

Get your endorphins flowing at one of the Rose Kennedy Greenway’s more than 200 free, open-air fitness classes. Throughout the week, you’ll find everything from Zumba to self-defense, meditation, parkour and strength training. This weekend, you could pump it up at a HIIT class (short for high intensity interval training) on Friday at 5:30 p.m. and Sunday at 9 a.m. Or find some peace at the Soma Summer Solstice outdoor yoga class on Saturday at 10 a.m. Also on Sunday: boxing at 11 a.m. with a New England Golden Gloves Champion and Pilates at noon led by Join Movement with Jill. The full summer fitness schedule can be found here.

Correction: A previous version of this article misstated the date of the ICA's Block Party at the Watershed in July. We have included an event happening this week in its place. We regret the error.