Leadville Trail 100 course

Source: The distance and the ascent are from the race organiser (leadvilleraceseries.com). We calculate the descent from the organiser ascent and the elevation difference between the start and the finish. The elevation profile and the gradient data come from a 10 m digital elevation model (NED (US)). All elevations are to the nearest 10 m (50 ft).

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About the course

The Leadville Trail 100 Run is a 100 mi161 km ultramarathon through the Colorado Rockies. It starts and finishes in the historic mining town of Leadville, at just over 10,100 ft3,080 m. The course is an out-and-back. It follows the shores of Turquoise Lake, climbs over Sugarloaf Pass and the Powerline, and passes Twin Lakes before crossing the Sawatch Range to the turnaround at the old ghost town of Winfield.

Known as the "Race Across the Sky," the course has 13,350 ft4,070 m of elevation gain and loss. It never drops below about 9,200 ft2,800 m and averages around 10,000 ft3,050 m above sea level. Its defining feature is Hope Pass, the course high point at c.12,500 ft3,810 m, which runners cross twice.

Runners must deal with thin air throughout, a crossing of the Twin Lakes wetlands and streams, afternoon thunderstorms, and near-freezing temperatures overnight.

The Leadville 100 course climbs and descends around 13,350 ft4,070 m over its c.100 mi161 km distance, much of it concentrated in the two crossings of Hope Pass. That's around 40% of the climbing on the Hardrock 100 and less than on the Western States 100. Its gain per mile is closer to that of the South Downs Way 100.

Ascent & descent analysis

In late August, Leadville days are usually mild, with temperatures typically around 21°C70°F, and the high altitude means intense sun. Nights are cold, often dropping to around 4°C40°F in town and close to or below freezing on Hope Pass.

Some rain is likely, and the tail end of the Colorado monsoon season can bring afternoon thunderstorms with heavy rain, hail and lightning. These are particularly dangerous on the exposed, above-treeline crossings of Hope Pass.

The weather data has been obtained using the Open-Meteo historical weather API.

Conditions at the start line

The pictograms below show the conditions at the start of the course on the race date in each of the last five years.

Temperature range on course

Temperatures experienced on course are impacted by elevation. The graph below shows the temperature range for the five most recent events at different parts of the course.

Daylight hours

The graph below shows the daylight hours on the day of the 2027 edition (21 August), in local time.

The Leadville 100 starts and finishes in Leadville at roughly 10,100 ft3,080 m, never drops below about 9,200 ft2,800 m, and climbs to around 12,500 ft3,810 m on Hope Pass. The entire race is spent at high altitude, so acclimatisation is a major factor, with thin air contributing to fatigue, breathlessness and altitude sickness risk throughout.