As the late, great Robin Williams once noted, “Spring is nature’s way of saying, ‘Let’s party!’” Certainly, longer days and warmer temps bring out the festive in all of us. Among the many ad hoc parties that crop up on the mountains, the best develop into annual traditions, transcending era. Unofficial and unsanctioned, but plenty of fun, these events have become as much a sign of spring as the robin for many local skiers and riders.

For almost 20 years on a late March/early April Saturday, the focus at Bonnie’s restaurant on Aspen Mountain shifts from strudel and soup to leis and lagers as local Sarah Manning hosts her Hawaii-themed Bonnie’s Bash on the deck. Scores of partiers sip Budweiser (until the kegs—now up to three—run out), nosh on burgers, and groove to the beats of DJ Mayfly. “People always think it’s my birthday, but it’s just a way to celebrate spring,” says Manning. If you see the deck going off as you ski by, click out, stop in, and raise a toast—or do a keg stand. 

Did you just pass a nun skiing on Easter morning, or see a gorilla chasing a bunch of bananas down a run? You either hit it too hard the night before or came upon the Four Mountain Crawl. Since 2010, Kate and James Spencer have planned the costumed and cocktailed celebration of Aspen’s four mountains on Buttermilk’s closing day. Joined by 30 or so fellow revelers, they ski top-to-bottom at one resort before hopping the bus to repeat at the next.

On April 15, one of Aspen’s longest-standing spring traditions, the Bell Mountain Buck-Off, hits its 47th year. Established in 1971 (one year it got rained out) by local ski gang the Buckaroos of Bell Mountain, this throwback to freestyle’s 1970s heyday is an all-out, costumed ski en masse down the moguls on Aspen Mountain’s Ridge of Bell. Always held at 1 p.m., the bump bash has become the unofficial swan song for the ski area’s closing day. Up to 300 skiers, including some rival ski gangs, show their stuff. But the only things rough and tumble about the event are the size of the bumps and the trash talk.