After weeks of sweating through the heat and humidity last August, Jeremy Silk Smith resolved to shave off his beard.

But between razor strokes, he had a thought: What if he kept the mustache?

“I was like, ‘This is going to be funny,’” the 28-year-old freelance writer tells The Post. He debuted his new “Chevron” ’stache — a full, bristly one — later that night, and his friends roundly approved.

“Everyone’s reaction was so good that I needed to keep it,” he says.

Goodbye, lumberjack beard: A substantial ’stache is the facial hair trend du jour among style-conscious men. Once a look favored by 1970s beefcakes, cops and porn stars, it’s making a steady comeback among leading men such as Eddie Murphy, Milo Ventimiglia and Paul Rudd.

“Bachelor in Paradise” contestant Dean Unglert recently rocked the trend as well — much to the horror of viewers — before shaving it to please his new girlfriend. Meanwhile, quirky Jacksonville Jaguars quarterback Gardner Minshew II’s old-school mustache has a cult social media following and is inspiring his hometown to wear fake facial hair.

“It’s just kind of symbolic of how we are as a team, just free, loose, we’re going to play as hard as we can, but we’re gonna have fun doing it,” Minshew, named the NFL’s rookie of the month on Thursday, told reporters of his signature look.

Like it or not, “the ’stache is back,” says Russell Maxwell, 37, who owns two eponymous barbershops in Brooklyn and has worked in grooming for two decades. “I think the beard has eased off,” he tells The Post. “The ’stache is the new thing.”

While a furry upper lip might be hip again, its comeback comes with more than a dash of irony.

While “it goes with all the cliche hipster things,” admits Maxwell, he says that classic mustachioed men are the inspiration: “Tom Selleck is the ultimate ’stache-daddy, forever. I think things always cycle back.”

“A lot more people have it now,” agrees Bedford-Stuyvesant bartender William Eidenback, 37, who’s been sporting a curly, carnie-style ’stache since 2007. At the time, he was a style outlier: “I grew mine out as a joke,” he admits.

The mustache revival can be traced, at least in part, to “Movember”: a global, month-long movement in which participants grow out their upper-lip hair to raise money for men’s health. According to the official Movember website, “The mustache had all but disappeared from fashion trends,” when, in 2003, a pair of charitable Australian pubmates came up with the follicular fundraiser. It has since become an international sensation, funding projects around the world.

While Minshew Mania is currently putting the ’stache back in the spotlight stateside, Maxwell says he’s noticed an upsurge in the bristled look across the pond, too. “I’ve seen quite a few ’staches in London…our hip generation likes to conform all over, so wherever it’s young and cool,” the mustache can be spotted, he says.

It’s also big “with gender non-conforming women and trans men,” says Luke Elmer, 40, a stylist at Maxwell’s barbershop in Bushwick. Elmer himself has sported a ’stache for 15 years, starting with a “curly doodad” that has evolved into his current walrus-like appendage. “I appreciate it as a facial accessory,” he says.

But for Eidenback, the style’s newfound popularity means he’s ready to move on. He admits he’s considering going barefaced to distinguish himself.

“I’ve thought about shaving it ’cause so many people have it now,” he says.