⏵ Course guide · Arizona fall night race
Mayhem runs the McDowell Mountain competitive track after dark on a cool early-December evening, sharing the trail with 50-mile runners finishing up the same day's McDowell Mountain Frenzy. The climbing is moderate and the cold, not the heat, is what you plan for. I will walk you through the course first, then give you a pacing and fueling plan built for a cool desert night race, with free calculators along the way to dial in your own numbers.
These facts come from the official Aravaipa race page. Check the current date, distances, cutoffs, and aid in the race-day details before you commit. Race logistics change year to year.
Mayhem starts from the Competitive Track Area at McDowell Mountain Regional Park and offers three distances, 25K, 10 Mile, and 5 Mile, on desert trail with moderate, scaled climbing. Now in its ninth year, it is a well-established addition to Aravaipa's fall calendar.
Because Mayhem runs the same December night as McDowell Mountain Frenzy, a daytime race with 5M, 10M, 25K, 50K, and 50M options, you will likely cross paths with Frenzy's longer-distance runners finishing up as you race. Expect a livelier, more populated trail than a typical solo night race, and give tired 50-mile finishers room when you pass.
Early December evenings in the Phoenix metro can drop into genuinely cool territory after sunset, a welcome change from the summer Insomniac races but still worth dressing for. Layer for a 5:00 PM start that only gets colder as the night wears on.
Finish any distance at both Mayhem and the daytime McDowell Mountain Frenzy and you earn a bonus Double Down medal. If you are running both, remember Frenzy starts at 7:00 AM, so your legs will already have real miles on them before Mayhem even begins.
With a generous cutoff window across every distance and cooler conditions than Aravaipa's summer night races, Mayhem is a good course to run at genuine effort.
Without summer heat working against you, you can run closer to your real trained pace here than at a hot-weather Insomniac race. Use a grade-adjusted pace target for the climbing so you still pace by effort, not just by how comfortable the cool air feels.
A vert-aware finish prediction built for this course gives you a realistic window against the 11:00 PM cutoff. Once you have that number, also plan mentally for slower sections where you are sharing trail with tired Frenzy finishers, since courtesy passes cost a little time you should already have budgeted for.
⏵ Free tools to pace this course
A 25K under a roughly 6-hour cutoff in cool December conditions is a modest fueling lift, but the cold changes your fluid and layering needs more than the distance changes your carbs.
Aim for roughly 45 to 75 grams of carbohydrate an hour for the 25K, scaling down for the shorter distances. Cold weather can blunt thirst and appetite, so eat on a schedule rather than waiting to feel like it.
Sodium in the 300 to 500 mg per liter range covers most runners in cool December conditions. It is easy to under-drink when the air feels cold and you are not visibly sweating, but you are still losing fluid through the effort, so keep drinking on the same schedule you would in warmer weather.
⏵ Build your fueling plan
Get a carb, sodium, fluid, and caffeine plan per hour built for your weight, your goal time, and a cool December Arizona night 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 McDowell Mountain course profile, and your projected splits. Summit Line reads your real training, builds a plan for cool night racing, and rehearses your fueling so race night is something you execute, not guess at.
Mayhem is a moderate desert trail race made distinct by its setting and timing: about 1,341 feet of gain over 15.2 miles on the McDowell Mountain competitive track, run entirely after dark starting at 5:00 PM on a cool early-December evening. Now in its ninth year (per the race's own description), Mayhem also shares the trail with 50-mile runners finishing the same day's McDowell Mountain Frenzy, which gives the course a unique, busier feel than a typical solo night race. The vert and distance are manageable for most trained trail runners; the main variables are the cold and the dark.
The 25K carries about 1,341 feet of total gain, topping out at 1,827 feet. The 10 Mile option drops to about 800 feet and the 5 Mile to about 500 feet, so the climbing scales down roughly in proportion to distance rather than concentrating in any one section.
Mayhem is the third of three night races Aravaipa mirrors against its daytime Fall Desert Runner Trail Series, timed to run the same evening as the daytime McDowell Mountain Frenzy at the same park. Early December in the Phoenix metro brings genuinely cool evenings, so the night start here is less about beating heat and more about giving trail runners a competitive-track night race and a real Double Down option with Frenzy.
All three distances share an overall 11:00 PM cutoff, which gives 25K starters roughly 6 hours from their 5:00 PM start, 10 Mile starters about 5.5 hours, and 5 Mile starters about 5.5 hours. That is a comfortable window across the board for a course of this size.
There is one full remote aid station, Gate Aid, plus a water-only stop that every distance passes each loop, in addition to the start/finish. Stations carry water, ice, electrolyte drink, salty and sweet snacks, fruit, PB&J, bean rollups, and hot food like quesadillas and grilled cheese as the night goes on.
It is a solid option for a first attempt at either. The vert is moderate and scales with your chosen distance, the loop format keeps aid and gear close, and the December evening cold, while real, is easier to dress for than summer desert heat. The one thing worth preparing for is sharing the trail with McDowell Mountain Frenzy's 50-mile field finishing up as you run, which is part of the atmosphere here, not a hazard, but good to expect going in.
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<a href="https://runsummitline.com/guides/mayhem-night-trail">The Mayhem Night Trail course guide</a>This guide is independent and for planning only. The course details, dates, distances, cutoffs, and aid 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.