Maybe it was the mix of lightning and snow that caused scores of runners to be treated for hypothermia during last year's Pikes Peak Ascent and Marathon.
Maybe it is the chilling effect the economy has on people's willingness to pay $95 to run up a mountain.
Maybe Pikes Peak mania just isn't what it once was.
Whatever the reason, the region's top running races, which in recent years have filled in minutes, still have plenty of open slots days after registration opened.
Every August thousands of racers jog, trudge and curse their way 7,815 vertical feet to the summit of Pikes Peak. Spots for the races were snapped up faster and faster until 2007, when, after first crashing the server of the registration Web site with thousands of hits, the Ascent filled in 25 minutes and the Marathon filled in 23 hours.
In 2008, race organizers began requiring racers to run pre-qualifying races in order to weed out less dedicated runners and soothe the registration process. Even so, all but the fastest wave of the Ascent filled in 67 minutes.
This year, something has changed. Both waves of the Ascent were only about 70 percent full Friday, two days after registration opened. The Marathon had a handful of spots left in both waves.
Runners posting comments on pikespeakmarathon.org blamed hard times.
"The economy over the past year has hit a lot of people hard. Seems like the price of admission keeps going up and folks who need to travel may not want to fork out the money for lodging, food, gas, airfare, etc.," poster Mike Wilkinson from Aurora wrote.
Another, calling herself Moongirl, replied, "Did the marathon last three years in a row, now unemployed from layoff. I'm out this year, pissed off, sad, uneasy time in our household."
Almost half of Pikes Peak racers usually come from out of state, filling local motels and restaurants as they turn race weekend into a vacation. These runners are likely hit hardest by the economy.
"Things are just too unsteady to spend away $1,500 on running up a mountain," wrote a former racer from Minnesota called Scream'n Turtle, who usually brings his family for a week. Others echoed his sentiments.
Registration organizer and perennial race winner Matt Carpenter said he thinks the economy is only a minor factor in the slower registration, compared to organizational changes race officials made.
For example, every year half of the people who sign up to run the Ascent and Marathon back to back have never done either.
"They run the Ascent the first day and are too tired to run the Marathon the next day," Carpenter said.
So this year, rules require racers to have run one of the races in the past before signing up for both. That move freed up about 100 spots in the Marathon.
But most other rules are the same as in 2008, and registration is lagging well behind what it was then.
The 2008 races, when snow, rain, hail and lightning caused over 1,000 runners to be turned back before the summit, could be a factor, Carpenter said.
"But is it a plus or a minus?" he said. "Part of me thinks people are so scared now they wouldn't come back. Part of me thinks anyone who didn't get to finish is gunning for another try."
Either way, he said, it will likely be months before all the spots fill, which, he added, is a good thing. "That means everyone who really wants to get in, will."