The San Francisco Peaks are the highest mountain range of Arizona, United States, and are located just north of Flagstaff in the north-central region of the state. The highest summit in the range is Humphreys Peak, 3,850 m (12,633 feet), situated at . They consist of the remains of a once-higher group of extinct volcanoes. An aquifer within the caldera supplies much of Flagstaff's water while the mountain itself is the site of much outdoor recreation.

The biologist Clinton Hart Merriam studied these mountains in 1889, describing a set of six 'life zones' found from the base to the summit of the mountains, based on the major components of their flora:

• Lower Sonoran Zone - Sonoran Desert plants
• Upper Sonoran Zone - Colorado Pinyon and juniper woods
• Transition Zone - Ponderosa Pine forests
• Canadian Zone - Rocky Mountain Douglas-fir and White Fir forest
• Hudsonian Zone - tree-line forests of Rocky Mountains Bristlecone Pine and Engelmann Spruce
• Arctic-Alpine Zone - alpine tundra
  

Merriam considered that these life zones could be extended to cover all the world's vegetation types with the addition of only one more zone, the tropical zone. His pioneering studies remained the one of the most widespread climate zone classifications, in use for nearly 80 years.

In 1629 one hundred and forty seven years before the California city received its name, in honor of the same saint, Friars founded a misson at a Hopi Indian village sixty five miles from the peaks. 17th century Franciscans at Oraibi village gave the name San Francisco to the peaks to honor St. Francis of Assisi, the founder of their order.

The peaks have considerable religious significance to local Native American tribes (Havasupai, Navajo, Hopi, and Zuni.) The mountain provides a number of recreational opportunities, including snow skiing and hiking. Hart's Prairie is a well loved hiking area nestled just below the mountain's ski resort.

Sudden and relatively unpredictable weather changes in Fall or Spring have resulted in unexpected snow fall bringing death from exposure to unprepared hikers. Native Americans sometime mention a legend that ghostly Kachina spirits appear during deadly snowfalls on the peaks.

The four highest individual peaks in Arizona are contained in the range:

• Humphreys Peak, 3,850 m (12,633 feet)
• Agassiz Peak, 3,766m (12,356 feet)
• Fremont Peak, 3,648m (11,969 feet)
• Doyle Peak, 3,493m (11,460 feet)

References

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Mountain ranges of Arizona

San Francisco Peaks | San Francisco-topparna