Agassiz Peak, Mountain summit in Coconino County, Arizona, US

Agassiz Peak rises to approximately 12,356 feet within the San Francisco Peaks range and is the second-highest mountain in Arizona. The summit is located in Coconino County and forms part of a connected mountain range that dominates the surrounding landscape.

The peak was named for Louis Agassiz, the Swiss-born American biologist and geologist. Since 1985 the trail to the summit has been closed because the loose, rocky ground threatens the San Francisco Peaks groundsel (Senecio franciscanus), a plant listed as threatened with critical habitat. The summit may be climbed only in winter, when snow covers the ground.

The peak lies within the Kachina Peaks Wilderness of Coconino National Forest, an area the Forest Service manages as a sacred landscape for Southwestern tribes. The mountain's name honours Louis Agassiz, the Swiss-born biologist and geologist, rather than any Native tradition. Above the treeline grows the San Francisco Peaks groundsel, a plant listed as threatened with critical habitat, which is why the upper slopes are closed to hiking outside winter.

Access to the summit is usually restricted to protect a rare plant species found at this elevation, with entry permitted mainly during winter months when snow covers the ground. Visitors should check current access regulations before planning a trip, as conditions vary by season.

At 35°19'33"N, Agassiz Peak is the southernmost summit in the contiguous United States above 12,000 feet (3,700 m). Because it stands between Flagstaff and Humphreys Peak, it hides the state high point from town, and many visitors mistake it for Humphreys.