As the wind howled and sleet pummeled the Lake Michigan shore on a 32-degree day, Rob Armstrong and a handful of students grabbed surfboards and headed toward the choppy waters.

Locals have a prideful glow when Californians learn there’s surfing in the Midwest, and it has little to do with board shorts and bikinis. Local waves are tastiest in the cold months. Instead of consulting tide charts, surfers study wind patterns like stock brokers devour earnings data.

Gnarly Hoosier waves don’t come from lunar tides. When there’s a strong wind blowing over Lake Michigan from the north, they're at their best. That wind, called fetch, shoves waves onto the south shore in Indiana towns like Gary and Michigan City, or over the border in Michigan.

“The better the fetch, the better the wave quality will be," said Brendan Heffernan, store manager at Third Coast Surf Shop in St. Joseph, Michigan.

Thick wetsuits help surfers weather the cold months as they drop into Midwestern waves.

Rob Armstrong, of Grand Rapids, Mich., teaches surf lessons at TCSS. “Once you're in the water and you get acclimated to it, like after the first five minutes of shock, you're like, ‘you know, this isn't too bad,’” he said.  “But when December, January rolls around, that's when it's a bit more hardcore.”

“You’ve gotta have a good entry and exit strategy if there’s ice. If the beachhead is frozen, it’s a must,” Armstrong said.

Still, local surf can be glorious. “I had a session three weeks ago that I was like, this is as good as a good day at a beach break in San Diego,“ Heffernan said. “People were stoked”

Heffernan said that even though waves and water movement in the great lakes are less powerful than in the ocean, people can drown. Even strong swimmers can get into trouble if they’ve never been in a wave before.

Isa Molter has wanted to learn surfing since she was a kid, and went on a trip to Hawaii last year. "I got up on my second try, which was shocking," Molter said. "It was an amazing feeling. It was like it felt like flying.”

In the Midwest, Lake Michigan gives Molter a chance to shred closer to home.

This article originally appeared on Indianapolis Star: Midwest surfers find waves and culture on an icy Lake Michigan