Still, a few stellar spots that were new then - Old City's romantic neighborhood-y Fork, for example, and even Safran's Lolita, with its house-made margarita mix and BYO-tequila policy - stayed steady. But overall, biz was down, mostly because patrons chose beach over bistro.
Rich Landau, co-chef and co-owner of the months-old and always-booked Vedge, explained the phenomenon plainly: "I mean, who wants to be in the city in August?"
Apparently, eaters do, more than ever.
These days, while local restaurateurs say summertime is still - in the words of Vetri's Benjamin - "soft," it's not nearly as mushy as it used to be.
Jillian Encarnacion, a manager at cocktail-crowded Twenty Manning Grill and chic BYOB Audrey Claire on South 20th Street, said business has been fairly booming this summer. "The week is busier, and the walk-in crowd is ridiculous on weekends," she said.
Oyster House owner Sam Mink is seeing more warm-weather customers later in the evenings and weeknights, too. Wednesdays, the Sansom Street seafood restaurant offers a special of two one-pound lobsters and corn on the cob for $26, and the place is packed.
"Center City has become a destination in the summer months," he said. "People think of us as a place to cool off, grab a cold beer and some raw oysters."
Still, the business crowd doesn't show up much for lunches, especially on Fridays, when they're rushing to take advantage of shorter hours.
Across town at Washington Square's half-al fresco Talula's Garden, co-owner Aimee Olexy has noticed a seasonal glut of patrons who come to "graze." She reported a lull early on Fridays evenings, but later on those nights, and on Saturdays, "People come out, drink a bunch of wine, have some snacks," she said, mentioning that their famous cheese plates are especially popular this time of year. Patrons "stay out, stay up and are more energized into the night."
Chip Roman, chef-owner of Conshohocken's Blackfish, Chestnut Hill's Mica and Queen Village's Ela, said his slowest times of the year are inevitably the last week in July and first week in August. "It's great for the customer," he said. "There are definitely a lot more choices in the summertime."
Still, business hasn't been bad at all, partly thanks to consistently high demand for high-rated Blackfish, and partly because Roman lures patrons to newbies Ela and Mica with tasting menus and guest chefs on off-nights. "We don't sit back and wait. We're definitely proactive," he said.
Thirty-seat Bibou, serving foie gras and escargots just a block from the Italian Market, is notoriously hard to get into. The typical wait for a reservation is six to eight weeks. Still, chef and co-owner Pierre Calmels said eaters have a better chance of scoring seats in summer, when his clientele often renege on reservations. Calmels' wife Charlotte gets the word out by tweeting when there's an opening. With a click of a mouse, that empty table is filled in no time.
Owners of Fork, the Oyster House, Lolita and others say more summer events at the Convention Center have done their part to help.
"It makes a difference," said Fork's Ellen Yin. "It helps everybody in the city."
Center City District, the community-development organization, credited their June-through-August "Sips" happy hours, wherein 90 establishments sling $3-$5 drinks and half-price apps Wednesdays 5-7 p.m., giving restaurants a midweek boost.
"Many restaurants will tell you if they didn't participate in Sips, it would not be a good scene," said Michelle Shannon, CCD vice president of marketing and communications .
If you take a look around on a Wednesday after work, she said, "You could physically see, outside on the sidewalk, people flowing over."
On the other hand, as Vetri guy Benjamin points out, the scene isn't necessarily overflow-y when the thermometer flows upward: "If it's 98 degrees at 6 o'clock at night, we're not going to have a busy night. The temperature in summer can be just as bad as having a snowstorm in the winter."
But despite the summer of 2012's extra-sticky swelter, business isn't bad. It's just . . . different. Which means those once simple-to-score 7:30 Saturday night reservations may not be so simple anymore.