How cold will it be in Minneapolis for the first-round NFL playoff game Sunday? Maybe it’s best if the Seattle Seahawks and Minnesota Vikings don’t ask for details.

The 1 p.m. EST game is expected to be among the coldest in NFL history. It will be so cold that Ticketmaster has urged fans to print their tickets in case mobile devices aren’t working at TCF Stadium. “All major cell phone manufacturers warn against using their product in extreme cold,” Ticketmaster wrote in its email.

But what about the guys on the field? What can they do about the temperatures? One thing they can do is wear special long johns. WSI, a Minnesota-based company, will supply special cold-weather gear for both teams.

“This has been a big break for us,” WSI Sports owner and founder Joel Wiens told USA Today. “I’ve spent most of my life pounding away, and we’ve been successful. But over the last few years, we’ve gotten noticed by designing better and better cold-weather gear.”

But there are other tricks of the trade, which former NFL player Matt Bowen shared in an ESPN blog post. For one thing, there’s a heat source that allows players to warm up (relatively speaking) when their unit isn’t on the field. Helmets also are heated. And then there are a couple of substances that secretly allow players to bravely bare their biceps in what is either a display of machismo or foolhardiness.

The first rule of staying warm is, of course, layers — especially gloves and socks. Everyone knows that. But too many layers gives opposing defensive players material to latch onto and may subliminally signal weakness. So Bowen, who played for Buffalo and Green Bay (and other teams) in a seven-year career, says players, like runners in cold weather, know the value of greasing up with petroleum jelly. It helps block the wind, believe it or not.

“Players want to show off their arms on a national stage in the playoffs, but to avoid shaking from the cold, you need to cover up with Vaseline,” Bowen writes. “It’s slimy and it takes some time to scrub off after the game, but it sure does work. And it’s much easier than wearing a ski mask under your helmet.”

Another secret weapon is those little, battery-operated handwarmers. “Among the many ways they are used: Drop a couple inside your hand muff, tape them to the top of your feet (before putting on cleats), put them in your gloves and tape them inside the ear hole of the helmet,” Bowen writes. “Back before players were required to wear leg pads, I saw guys put them in the thigh board slot of the game pants.”

Sideline heaters are wonderful, but they’re also dangerous. They’re “like jet engines. And it’s a good idea to stand in front of those before taking the field, especially for special teams (limited reps lead to tight hamstrings in the cold),” he writes. “However, those things are dangerous. I mean, it’s an open flame.”

Bowen urges players to sit on the heated benches (warming up the area to around 40 degrees) and to use the helmet warmers (or risk losing an ear). The helmet warmers “are attached to the back of the heated benches (long, white poles) and are a must for any player. Putting on an ice-cold helmet is terrible — those pads inside freeze instantly in the cold, and your helmet turns into a brick. Good luck squeezing that thing on while avoiding the possibility that your ears might rip off your dome.”

And there’s the obvious solution: drink something hot. Bowen suggests hot chocolate and chicken broth but warns that “you can’t just pound that stuff. No one wants to drink five cups of hot chocolate and then run down on the opening kickoff. That’s trouble, and it also leads to vomit all over the field. Yes, you have to continue to hydrate during cold-weather games (I once cramped up during a game in Buffalo), so Gatorade, Pedialyte and water are a must before and during the game. A cup of hot chocolate in the locker room and a cup of chicken broth while you get a break on the sideline, however, is a smart way to stay warm.”

Doesn’t sound so bad, does it? It’s a far cry from the old-school way in which former coach Bud Grant ran things with the Vikings decades ago and it’s only temporary, with the Vikings set to move into a covered stadium next season. Cold weather is all in your head.

“You don’t stay warm,” Grant told The Post’s Adam Kilgore. “You’re cold. So what? We never had anybody who froze to death playing football. You probably had somebody who died from heat stroke playing football.”

Well, yes. The 2001 Vikings lost tackle Korey Stringer to heat exhaustion in training camp.

“The hardest thing will be for the fans,” Grant said. “There’s not enough schnapps and blackberry brandy to keep them warm.”