Javelina Jundred 100 Mile Endurance Run

Javelina Jundred 100 Mile Endurance Run is held in Scottsdale, Arizona, on October 31, 2026. The organizer's website points to Aravaipa Running. Three trail formats are on the schedule: the 100-mile race starts at 6:00 AM, the 100K (62 miles) at 7:00 AM, and the Jackass 31K (about 19.3 miles) at 6:00 PM. The Halloween date and the playful names set the tone for a desert ultra with a festive side.

The Sonoran Desert around Scottsdale is warm even at the end of October, and the 100-mile runs from a cool morning into midday heat and back into a cold night. Heat training, a steady fluid and electrolyte routine, and layers for the night are key parts of your preparation. The 100-mile is a popular choice for a first 100 because the terrain is runnable rather than mountainous; a 20 to 24-week build with back-to-back long runs is a typical approach. The 100K suits runners moving up from 50 miles, and the evening 31K is a chance to run the desert trails under headlamp.