Outdoor bars have become popular in recent years, as the concept of the beer garden has taken hold.

The Pennsylvania Horticultural Society's annual pop-up beer gardens are big draws. This year, the South Street location (near 15th Street) is operated by Cantina Los Caballitos. New this year is a second pop-up location at UCity Square, on a vacant lot at 36th and Filbert Streets in University City. PHS is going for an open-air, European-style garden. Jet Wine Bar, a 2017 Readers' Choice winner, will operate the garden, with food by sibling restaurants Rex 1516 and Café Ynez.

The season's big newcomer will be Tria Wine Garden, set up on a new patio outside the United Plaza (31 S. 18th St.). It will be a partnership between the popular Tria and Four Corners Management, which oversees several local bars, including the outdoor destination Morgan's Pier.

The other major undertaking is a second season for Parks on Tap, the traveling beer garden -- sponsored by the Fairmount Park Conservancy, Philadelphia Parks and Recreation, and FCM Hospitality -- that spends a few days in various verdant locations.

Some other warm-weather highlights:

1717 Arch St.
The 51st-story views from Three Logan Square really jazz up this indoor/outdoor beer garden. New this year: a slushy machine for frozen cocktails and pagers that buzz when patrons' food orders are ready.

Morgan's Pier
221 N Christopher Columbus Blvd
Chefs Michael Griffiths and Kevin D'Egidio of Helm and South Helm are at the stove this summer at this massive playground under the Ben Franklin Bridge. Menu includes puffy, pizza-like "fatbreads" by baker Alex Bois.

Spruce Street Harbor Park
301 S Christopher Columbus Blvd
The hot venue along the Delaware at Penn's Landing will have 25 more reasons to chill this year -- as in, 25 new hammocks, bringing the total to 50. The park also will add eight draft lines to the beer garden -- two of which will be dedicated to a selection of rotating draft cocktails. The restaurant lineup includes Chickie's & Pete's, Franklin Fountain, Frozen Delights, Garces (serving new boardwalk-style pizza) and Federal Donuts, a 2017 Readers' Choice winner.

Independence Beer Garden
100 S Independence Mall West
Michael Schulson of Sampan and Double Knot operates this massive setup across from the Liberty Bell.

1901 South 9th St.
The pop-up bar on the roof of the former Bok High School in South Philadelphia will operate Wednesday to Sunday.

Evil Genius Brew Garden
1727 Front St.
The Fishtown brewpub's outdoor setup springs to life.

Uptown Beer Garden
1735 Market St.
The pop-up outside BNY Mellon adds a fourth bar this season.

The Deck at the Moshulu
401 S Christopher Columbus Blvd
The floating restaurant at Penn's Landing, whose decks offer incredible views of the river, the city skyline, and Ben Franklin Bridge, opens its bars from 3 to 10 p.m. weekdays, noon to 11 p.m. Saturday, and 10 a.m. to 2:30 p.m. for Sunday brunch, followed by 3 to 11 p.m. for dinner.

Dilworth Park Café & Air Grille
1 S 15th St.
Outside City Hall, there's beer, wine, and cocktails after 5 p.m. Monday through Friday and all day Saturday and Sunday.

East Falls Beer Garden
4100 Ridge Ave.
On the third Thursday of the month (in the parking lot between In Riva and the Trolley Car Diner), a collection of food trucks and vendors pops up from 6 to 11 p.m.

And of course, there's Center City Sips, a Wednesday after-work discount promotion among bars and restaurants. It wraps Aug. 30 this year.