TAHOE CITY, Calif.—On most July 4ths, Scott Grosso barbecues with his friends and family in Cupertino, Calif. This year, he has different Independence Day plans: He's strapping on his snowboard.

"I plan on getting up early in the morning and snowboarding all day, then go down to the deck for some barbecue and cocktails and enjoy the 70-degree weather" in Lake Tahoe, says the 38-year-old. "I keep rubbing it in to all my friends in Connecticut. They can't believe it."

Mr. Grosso can't quite believe it, either. Skiing or snowboarding on the Fourth of July is typically hard to do in the continental U.S. But in Northern California's Lake Tahoe region this summer, the mountains are still packed with snow after an extended winter pounded the Sierra Nevada range and dumped fresh powder onto the area well into June. More than 15 feet of snow still remains atop some mountains.

That means for the first time since the mid-1990s, at least four Tahoe-area ski resorts are advertising that they will be open over the holiday weekend. And that is attracting a flood of ski fanatics, many of whom consider it a badge of honor to hit the slopes on Independence Day.

"We're not so excited about the skiing—it's the bragging rights. It's the, 'Ha! We did go," says Suzanne Hirabayashi, a 48-year-old Homewood, Calif., resident, who last skied July 4th in 1995.