Summit Line

⏵ Course guide · New Mexico ultra

Jemez Mountain Trail Runs Course Guide

The Jemez Mountain Trail Runs are New Mexico’s flagship mountain ultra, run out of Los Alamos up in the Jemez Mountains and the Santa Fe National Forest, and the 50 mile is genuinely one of the toughest in the Southwest: roughly 12,000-plus feet of climbing, a high point around 10,400 feet you cross twice, and steep technical trail the whole way. I’ll walk you through the course first, then give you a pacing and fueling plan that respects the vert and the altitude. There are free calculators along the way to dial in your own numbers.

⏵ At a glance

Jemez Mountain Trail Runs quick facts

Date
Saturday, May 9, 2026 (typically the second Saturday of May)
Location
Posse Lodge, North Mesa, Los Alamos, NM (Jemez Mountains, Santa Fe National Forest)
Distances
50 mile (closer to 53 mi on the ground) · 50K · 15 mile
Elevation gain
50 mile: roughly 12,000+ ft of climbing, high point around 10,400 ft (hit twice)
Start
50 mile 5:00 AM · 50K 6:00 AM · 15 mile 8:00 AM
Cutoff
50 mile: 8:20 PM overall at Mitchell (mile 49), with hard intermittent cutoffs and a forced switch to the 50K if you miss them
Qualifier
ITRA-rated 50 mile, long used as a Hardrock and Bighorn buildup; confirm current qualifier status with the race

These facts come from the official race site, the Team RunRun race info, and ITRA. Check the current date, cutoffs, and aid stations in the runners manual before you commit. Race logistics change year to year.

The course: where Jemez is won and lost

The 50 mile starts at the Posse Lodge on North Mesa in Los Alamos and spends the whole day up high in the Jemez. Figure closer to 53 miles on the ground, roughly 12,000-plus feet of climbing, about ten aid stations, and a high point near 10,400 feet that you go over twice. It is rugged: runnable singletrack in places, but also scree, stream crossings, downed timber, and a few off-trail pitches. The 50K is the same character on a shorter loop, and the 15 mile is the friendly way in.

The big climbs: long, sustained, and higher than they feel

Jemez is a vert day, not a distance day, and it is decided on the climbs. There are two big sustained efforts in the 50 mile (one in the neighborhood of 2,600 to 2,800 feet) plus a couple of mean short pitches that gain close to 900 feet in barely over half a mile, including the haul up toward Pajarito. At altitude these climbs feel longer than the numbers say, and the false summits will mess with your head if you let them. Hike the steep parts efficiently, keep your effort even, and get to the top of each one with legs in reserve.

The single biggest mistake here is treating the early miles like they are free. They are not. Push the first climbs because the air still feels okay and you will pay it all back, with interest, on the second pass over the high point late in the day.

The descents: technical, fast, and quad-killers

What goes up comes down steep and rocky. The descents at Jemez are genuinely technical in spots, with scree, loose footing, and timber to pick through, and they will trash your quads if you have not trained for them. The runners who finish strong are the ones who can still descend with control in the back half, when their legs are cooked and the trail is not getting any smoother.

Practice real downhill running on rough trail before race day, not just road downhills. Being able to keep your feet moving and your braking under control on a chewed-up descent at mile 40 is what separates a solid finish from a long, careful limp to Mitchell.

Altitude, exposure, and the long gaps between aid

You spend the whole day between roughly 7,000 and over 10,000 feet, so the altitude is a real opponent even if you are fit. It steals your top-end, dries you out faster than you expect, and makes eating harder the higher you climb. Up on the high traverses you are exposed to strong sun, wind, and the occasional spring snow, so the weather can swing on you.

Aid is well stocked but spaced out, with the longest carry on the 50 mile running around nine miles, and it is a cupless race. Carry your own flask or cup, and pack enough fluid and calories to actually cover those gaps instead of rationing to the next station and showing up empty. Do not assume the next aid is close.

The cutoffs and the forced switch to the 50K

Jemez runs hard intermittent cutoffs on the 50 mile (think Camp May Road, the Ice Rink, and Mitchell), and the overall finish cutoff at Mitchell the second time lands around 8:20 PM. Here is the part that is actually kind: if you miss an early cutoff, you usually get moved to the 50K rather than pulled off the course entirely, so a rough morning does not have to end your day.

That structure means you cannot bank all your buffer for the end. Know your splits into each checkpoint, build in margin for the climbs and the altitude, and keep moving through aid. Pacers are allowed on the 50 mile from Mitchell (mile 33.8) onward, so if you have crew, that is where a fresh set of legs and a clear head pays off most.

Pacing strategy for a high, climbing-heavy ultra

With 12,000-plus feet of gain and a high point you cross twice, Jemez is about managing effort at altitude, not chasing a pace chart. Run the climbs by feel, give the altitude its due, and protect your legs for the second half.

Pace the climbs by grade and effort, not the watch

Your flat-ground pace is meaningless on the Jemez climbs, and it is doubly meaningless at 10,000 feet. What matters is grade-adjusted effort: hold a steady output you can actually sustain up the grade, and hike the steep pitches without guilt. The trap is running the early climbs hard because the air still feels fine, then unraveling on the second high crossing. Use a grade-adjusted pace to turn your real fitness into honest climbing and descending targets so you do not torch the first half.

Build a vert-and-altitude-aware finish prediction

Do not guess your Jemez finish off a road 50 mile or a flat 50K. The 12,000-plus feet of climbing, the technical footing, and the thin air all add real time, and they add it unevenly across the day. A vert-aware finish prediction gives you a realistic window and, just as important, lets you work backward into those intermittent cutoffs so you know how much buffer you carry into Camp May Road, the Ice Rink, and Mitchell instead of finding out the hard way.

⏵ Free tools to pace this course

Fueling strategy for altitude and a long day

Most runners are out on the Jemez 50 mile for the better part of a day at altitude, with dry air and long climbs both working against your appetite. That makes carbohydrate, sodium, and fluid as important as fitness.

Carbs: steady, trained, and easy to get down

For a day this long, aim for roughly 60 to 90 grams of carbohydrate per hour, and only push the higher end if your gut is genuinely trained for it. Altitude and the climbing both kill your appetite, so the higher and later you get, the harder eating becomes. Keep your intake steady and easy to swallow rather than gambling on big late doses, and practice your exact race-day carb rate on long climbs so it feels normal, not like an experiment you are running on race morning.

Sodium and fluid: plan for dry air and the nine-mile gaps

Dry mountain air pulls more water out of you than the cool temps suggest, so do not under-drink just because it does not feel hot. Lean sodium toward the high end, often 500 to 700 milligrams per liter, and more if you are a heavy or salty sweater. Then carry enough fluid to cover the long carries, since the widest aid gap on the 50 mile runs around nine miles and it is a cupless race, so bring your own flask or cup. Weigh yourself before and after a long climb in dry conditions to find your real sweat rate, then build the plan around your own number.

⏵ Build your fueling plan

Get a carb, sodium, fluid, and caffeine plan per hour built for your weight, your goal time, and the Jemez altitude with the free ultra fueling calculator. Browse the rest of the free running tools at the tools hub.

⏵ Train for it with Summit Line

Get a race-day plan built around YOUR fitness, this exact Jemez course profile, and your projected splits. Summit Line reads your real training, builds a plan for the big climbs and the altitude, and rehearses your fueling so race day is something you execute, not guess at.

Start free →Explore the demo

Jemez Mountain Trail Runs FAQ

How hard is the Jemez Mountain Trail Runs 50 mile?

It is one of the harder 50-milers in the Southwest, full stop. The 50 mile runs closer to 53 miles on the ground with somewhere north of 12,000 feet of climbing, on rugged technical singletrack that tops out around 10,400 feet, and you hit that high point twice. Add scree, stream crossings, downed timber, and thin air, and you get a course people use as a buildup for Hardrock and Bighorn. The cutoffs are real and there is a forced switch to the 50K if you fall behind, so steady climbing, smart altitude pacing, and a fueling plan matter more than raw speed.

How much climbing is in the Jemez 50 mile and 50K?

The 50 mile stacks up roughly 12,000-plus feet of total climbing over its ~53 miles, with two big sustained climbs (one in the neighborhood of 2,600 to 2,800 feet) and a couple of nasty pitches that gain close to 900 feet in barely over half a mile. The high point sits around 10,400 feet and you go over it twice. The 50K is the shorter sibling but it is still a serious mountain day with steep technical climbing and descending, not a runnable 50K. Treat both as vert days, not distance days.

What are the cutoff times for the Jemez Mountain Trail Runs?

For the 50 mile, the day is governed by intermittent cutoffs: Camp May Road around 3:00 PM (mile 21.7), the Ice Rink at noon (mile 24.7), and Mitchell the first time around 2:20 PM (mile 33.8), with the overall finish cutoff at Mitchell the second time around 8:20 PM (mile 49). Miss the early ones and you get moved to the 50K rather than pulled, which is a kinder rule than most races run. The 50K has its own cutoffs (Camp May Road ~3:00 PM, Ice Rink ~5:00 PM, Mitchell ~8:20 PM), and the 15 mile has no hard cutoffs but expects you to finish in roughly seven hours. Confirm the exact times in the current runners manual before race day, since they shift year to year.

How should I fuel for the Jemez 50 mile?

Plan for a long day at altitude where the dry air and the climbing both blunt your appetite. Most runners do well on roughly 60 to 90 grams of carbohydrate per hour, leaning to the higher end only if your gut is trained for it, and you want to keep that intake steady because it gets harder to eat the higher and later you go. Sodium and fluid matter a lot in dry mountain air, so dial sodium toward the high end (often 500 to 700 mg per liter) and carry enough to cover the long gaps, since the widest aid spacing on the 50 mile runs around nine miles. It is a cupless race, so bring your own soft flask or cup. Run your own numbers for your weight, goal time, and the forecast with the free ultra fueling calculator.

What is the terrain and weather like at Jemez?

The course is rugged, high, and technical: runnable singletrack in stretches, but also steep scree, stream crossings, fallen timber from old burns, and a few genuinely off-trail bushy pitches. You spend the day between about 7,000 and over 10,000 feet, so the altitude is a real factor even for fit runners. Early-to-mid May in the Jemez means big temperature swings and dry air, with averages around a 63-degree high and a 40-degree low, plus strong high-altitude sun up top and the chance of cold, wind, or even snow on the high traverses. Pack for both ends of that range.

Should the 50 mile or the 50K be my first Jemez race?

If Jemez is your first crack at the mountains here, the 50K is the smarter entry point, and there is no shame in it: it is still a steep, technical, high-altitude ultra. The 50 mile is a big, committing day that rewards people who have trained long sustained climbs, practiced technical descending, and spent time at altitude. Either way, get specific in training: long climbs and descents, time on rocky technical trail, and a fueling and hydration plan you have rehearsed. If you respect the vert and the altitude, the generous cutoff structure gives prepared runners a real shot.

This guide is independent and for planning only. The course details, dates, cutoffs, and aid stations come from public sources and can change year to year, so confirm the current specifics with the official race before you register or run. The fueling and pacing advice is general and not medical advice.