“Hot weather opens the skull of a city,” wrote New Orleans-born Truman Capote, “exposing its white brain and its heart of nerves.”

Don’t it, though? The Crescent City in the soupy season has been known to bring on brain fever. Tempers flare, foreheads crack like expired pralines and businesses close shop until the school bell rings. Those “out there” look like “walkers”: feverish, half-baked, menacing. Road rage, domestic abuse and killer-mime hallucinations ensue. Crime rates keep pace with the soaring mercury. Locals stuck in town hole up and wait it out, allowing the tourists to take over.

Relax, there is respite. August here is when Hell freezes over inside bars and restaurants, the city’s ice palaces, which provide just the chill-pill to meltdown. (Warning: side effects may include dizziness.) The city’s makeshift igloos ramp up their air conditioning like no other metropolitan hot pocket. And though, by average, most are set at 73 degrees, that seemingly modest figure invariably feels far more brisk when out on the street it’s frying.

“When you go out to have a drink or eat here in the summer you know to bring a sweater,” said Genevieve Cullen, a bartender at Bud Rip’s Old 9th Ward Bar (est. 1960), which was cited as a cold front by several veteran barkeeps and night crawlers recruited as Advocate cold-front panelists. (None included their own digs as cold front candidates.) On a recent afternoon, Bud Rip’s proved more reasonable than chilly — though its new owners were in the throes of overhauling its AC system.

“If you’ve lived here a while, you know to bring a light wrap to a restaurant or a movie theater,” echoed Susan Spicer, the chef of the French Quarter’s Bayona and Mondo, in Lakeview.

Where to chill?

So what are the ultimate cold fronts for swilling and sustenance, day or night? (We wouldn’t dare to deem any of them THE sole cold rooms.)

Check the temperatures on wall units all you like, but they’re not an entirely reliable gauge. There are mirages at play, deceptive but subliminally effective. Among the factors aligning to create snowball effects are an interior’s décor (spaces that are industrial, uber-Modern or simply sparse in furnishings exude cool), flooring (tiled or concrete are colder), ceiling height, and direct (or not) natural light exposure. If it’s a mole hole, it will likely be colder.

And there are crannies suggestive of haunted “cold spots” in otherwise comfortable rooms, that deliver shivers up the spine. Case in point: the Columns Hotel, where an AC vent positioned under a certain corner perch at the bar blasts frigid air up dresses and trouser legs.

New Orleans cold fronts, we discovered, invariably include sepulchral dive- and sports bars, sushi-and-steak houses, booze-friendly movie theaters, cigar lounges with their humidors and fat-cat clientele, vegetarian outposts, jacket-required establishments and all those f-f-f-frozen daiquiri factories indigenous to Veterans Highway and Bourbon Street.

“The challenge with daiquiri places is this: Are you cold because you are drinking them or because the bar is cold?” pondered Virginia Saussy, a marketing consultant for the Warehouse District’s Lucy’s Retired Surfer Bar & Restaurant, known for its “Arctic Shelf Pleasers,” such as Tito’s Frozen Lemonade. “Boozer’s dilemma,” she shrugged.

As for perception-versus-reality venues, a case in point is Uptown’s Brothers III Lounge, which is cooled by multiple wall boxes and deemed “butt-freezing” by a quartet of social-coasters on our makeshift team, most with penchants for black-tie and for slumming it.

On a Thursday afternoon at Brothers III, a surly barkeep growled, “I have no idea what the temperature is in here. Maybe 70? But we’re the coolest bar in town, and we got the coldest beer in town.” As evidence that it was “cold all right,” he added, “I may be the only bartender here who wears long pants and a long shirt to work in the summer.”

Not the only one, actually. At Dos Jefes Uptown Cigar Bar on Tchoupitoulas Street, a bartender pointed to the blue jeans he wore to work to keep warm. He explained the wavering mercurial conditions (72 at that moment). “It’s colder now because it’s slow. Once the bodies roll in, though, it’ll ramp up the heat,” he said. And the temperature setting is lowered.

Source of pride

“It actually makes us pretty happy when someone eating at Mondo says, ‘It’s a little chilly in here,’ said Spicer, “because when we first opened four years ago, the AC wasn’t working right and it was hot, hot, hot. But once we added five more tons (of AC capacity) things got a lot better. Maybe we’re overcompensating now, but we do tend to keep thermostats set on 72.”

At the Riverbend’s New Orleans Original Daiquiris, a server reached by telephone placed the average temperature at 72. “We keep the settings in locked boxes to keep customers from turning it down,” she said. But on multiple visits we found the double-meters, encased in plastic, holding steady at 69.

Which is just how Tory McPhail, executive chef of Commander’s Palace, likes it: walk-in frigid. “It’s certainly cold at that daiquiri place,” he said, “but it’s also a cool spot to hang out because it’s more of a broad swath of residents — from judges to junkies — than anywhere I can think of … except maybe Central Lock-Up, which is certainly cold-hearted.”

He and others chose Port of Call in their top three of freeze-outs. “Besides being cold inside, the Monsoons have so much liquor in them that a layer of frost builds up around the outside of the go-cup,” McPhail said. “Cools me just thinking about it.”

Sean Meenan — a New York restaurateur and New Orleans transplant who’s feeling the heat from French Quarter residents over his envisioned Café Habana on Rampart and Esplanade — resides mere blocks from Port of Call. He too calls it “one cool oasis. You leave the outside behind when you enter.”

It isn’t so much the AC setting (72), so much as the positioning of the vents, which blast from all directions, including from above. On an early afternoon visit, a herd of customers wallowed outside the door in the 96-degree heat. When this reporter attempted to shake pepper onto a cheese-cloaked spud, it blew starboard onto a neighbor’s burger.

Back in the 60s

Likewise, beef people Mr. John’s Steak House, the Lower Garden District fixture, made the coldest Top 3. “It’s a f---ing iceberg in there!” said Brian Bockman, a Garden District architect who frequents the St. Charles Avenue restaurant. On an early bird visit, the maitre’d allowed that the temperature was 69 inside.

Restaurateur Robert LeBlanc — whose Lower Garden District whiskey bar Barrel Proof keeps its AC set at 65 when the doors are open to the street — said Mr. John’s was gloves-down the coldest restaurant in town. “I don’t know any colder dining room … or steakhouse. And they’re all pretty cold.”

Alternately, meat-averse Seed on Lower Prytania is “completely freezing too,“ said Bockman, “Probably due to the fact it’s vegan.” A weekday lunch visit found the temperature set at 73, but ceiling fans, concrete floors and a melon color palette in the cucumber-cool room spread the crisp-air love.

Then there’s the dress code-rigid Galatoire’s (owned by Advocate publisher John Georges), also a top ice pick. With its 60 tons of AC on the first floor alone, Galatoire’s keeps the temperature at 68, said president and CEO Melvin Rodrigue. “It’s all about the humidity,” he said.

“When August rolls around, I seek safe — and very cold harbor — at Galatoire’s, where they always keep the icy martinis and cold Sancerre coming,” said Julia Reed, vocal local and author of “But Mama Always Put Vodka in Her Sangria!”

Reed called it a tie between Galatoire’s and the AMC Elmwood Palace 20 for cold spots, the latter “where a frozen margarita makes even the most mundane summer blockbuster entertaining.”

Tom Sancton, a clarinetist and author who gigs at the Palm Court Jazz Café, Preservation Hall and Snug Harbor, wholly concurred, seeking Arctic air at Elmwood. “None of the jazz clubs I play at really fit the freezing bill,” he said. “A lot of them on Frenchmen Street have open doors.”

Also cold

Yes, we know there are so many untapped cold spots out there that eluded our three-week sledding expedition. Try not to sweat it; lift a frosty mug instead.

Here’s our short list of freeze-factor runners up: the French Quarter’s Fahy’s Irish Pub (on Burgundy), uptown’s Superior Seafood, Grit’s Bar and Clancy’s, the Riverbend’s Cooter Brown’s, the Roosevelt Hotel’s Sazerac Room, Liuzza’s (Mid-City), and, as a whole, Harrah’s Casino … where, of course, cooler heads prevail when the chips are down.