Colorado ski resorts are expected to see a significant rise in visitors over the next few weeks while schools let out for the spring, and the Colorado Department of Transportation is warning those visitors about high elevations.

“Even moderate consumption of cannabis or alcohol can lead to a stronger impact than expected,” the department said in a Friday news release addressing the potential dangers of driving under the influence of marijuana or alcohol at higher elevations.

While multiple studies have found that alcohol does not affect people more at higher elevations, the symptoms of being at a higher elevation — along with the usage of cannabis or alcohol — can heighten impairment. 

Ultimately, traveling to higher elevations can lead to quicker dehydration, increased fatigue and less oxygen, leading to quicker and more drastic impairment when partaking in alcohol or cannabis, the department said.

“We’re reminding visitors that much like skiing, driving demands your complete attention and focus,” Sam Cole, CDOT communications manager, said in the release. “A drink or edible that feels mild at sea level can have a stronger effect in the mountains. For spring breakers this can lead to risky behaviors, including getting behind the wheel while impaired.”

There were 203 fatalities on Colorado roads in 2024 that involved an impaired driver, accounting for 31 percent of all traffic deaths during the year, CDOT said. Last year, law enforcement agencies in Eagle and Summit counties issued more than 120 DUIs between February and April during impaired driving enforcement periods.

Drivers can be arrested and cited for DUI or DWAI if law enforcement observes a driver is impaired, even if their breath or blood tests show THC and alcohol levels below the legal limit, CDOT said.

“Every year, we see a spike in DUIs during spring break, many of which involve visitors who underestimate altitude’s impact on alcohol impairment and the potency of cannabis products,” Summit County Sheriff Jaime FitzSimons said.