All-Out Spring Fever

Lace up for an unforgettable start to spring at the All-Out Spring Fever, returning to Golden, Colorado, on March 22, 2026. This popular event, now in its 14th annual running, offers a choice of a Half Marathon (13.1M), 10K, or 5K, catering to both seasoned athletes and those new to racing. The courses are renowned for being challenging yet rewarding, winding through the spectacular foothills of Colorado's Rocky Mountains, with a start and finish at Jefferson County's NAAC Stadium. Runners will experience National Park-like views, hugging the scenic shores of Arvada's Blunn Reservoir via the Ralston Creek Trail, and may even spot local wildlife along the way.

The half marathon course, known for its challenging inclines, includes an out-and-back section on the Ralston Creek Trail before looping around Blunn Reservoir, featuring some hills that can climb around 650 feet in elevation towards the later miles. To support runners through these picturesque demands, the half marathon boasts eight fueling stations stocked with water, energy drinks, Gatorade, and gels. Typical race day conditions in late March bring pleasant temperatures, with highs around 58°F and lows around 33°F, and only an 8% chance of precipitation, creating ideal running weather.

Beyond the stunning scenery and well-supported course, the All-Out Spring Fever is part of the "Endless Series" alongside its fall counterpart, the Kooky-Spooky. Participants receive a swag bag including a stainless steel water bottle, brag tag, souvenir race bibs, and a custom sticker, with a finisher's medal awaiting all who cross the finish line. Free race-day pictures capture your achievements, and the event proudly supports UpRoot Colorado. This race also offers an opportunity to qualify for your BOLDERBoulder wave.