Arizona Trail Weather Planner

The Arizona Trail presents some of the most extreme elevation variation found on any National Scenic Trail. The route climbs from approximately 4,800 feet at the Mexico border, surges above 9,000 feet through the Santa Catalinas, Mazatzals, and San Francisco Peaks, and descends to the Colorado Plateau near the Utah border. This dramatic relief means that a single day's hike can swing from scorching desert heat to near-freezing conditions, and hikers need to be prepared for it.

For most thru-hikers, the primary weather concern on the Arizona Trail is heat. The desert sections (the Sonoran Desert corridors south of Tucson, the lower Gila River drainage, and the high-desert grasslands) can see apparent temperatures well above 100 °F during spring and early summer.

The higher-elevation sections can experience severe wind chill, particularly outside the primary spring hiking window. A wind chill advisory is shown by the Weather Planner tool whenever apparent low temperatures are expected to fall to or below 20 °F, the approximate gear-rating floor for most standard cold-weather hiking equipmen (without purchasing more expensive specialty gear). This threshold is independent of the formal Wind Chill Watches, Warnings, and Advisories issued by the National Weather Service, whose thresholds vary by region and season. Always check your local NWS forecast before heading into high-elevation terrain in cold conditions.

The weather data used by TrailTemps comes from Open-Meteo and is generated at approximately 9-kilometer resolution. In Arizona's rugged terrain a single grid cell can span canyon floors and ridgeline crests that differ by thousands of feet in elevation. When the actual trail point sits well above or below the grid's reference elevation, the apparent temperature (much less the actual temperature data) will not accurately reflect what a hiker on the trail will experience. TrailTemps applies the following elevation-based corrections to apparent temperature for each Arizona Trail waypoint. This is not an exact science (there are way too many variables involved), but it should give a reasoanble approximation for long-term planning purposes.

• Trail Significantly Above Weather Grid: At higher altitude the atmosphere is thinner and this reduced thermal mass at exposed heights can reduce temperatures both night and day. Therefore, during the day, an adjustment of +3.5 °F per 1,000 feet elevation difference is possible and this is applied to the expected apparent high temperatures. However, at night this cooling effect can be slightly offset by warm air from the valleys rising up the mountain sides, so the expected increase to the apparent low temperatures is a bit lower at only −2 °F per 1,00 foot elevation difference.
• Trail Significantly Below Weather Grid (canyon bottoms, desert basins): During the day canyon walls can absorb and re-radiate heat, trapping warm air and driving ground-level temperatures above what surrounding terrain or grid data suggest. An adjustment of +3.5 °F per 1,000 feet below the grid elevation is applied to apparent highs in these cases. Apparent lows, however, are not adjusted, since cold air can "drain" into canyons at night and this tends to approximately offset the various heating effects encountered during the day.

• Trail Route: The Arizona Trail runs approximately 800 miles from the Mexican border at Coronado National Memorial (near the town of Hereford, AZ) north to the Utah state line at Stateline Campground. The trail is organized into 43 numbered Passages maintained by the Arizona Trail Association. This planner groups those passages into three broad regions, 1) Southern, 2) Central, and 3) Northern Arizona to make navigation easier.
• Alternate Routes: Near Flagstaff, the Arizona Trail offers two route options through the area. The main route traverses the San Francisco Peaks wilderness, passing through high alpine terrain above 11,000 feet.
  
  The Flagstaff Urban Alternate descends into the city of Flagstaff (allowing hikers to resupply) and rejoins the main route on the far side of town. There are also a few side spurs and mountain bike trails that connect to various portions of the AZT, but as they are not part of the primary route and are not used by the typical through-hiker, they have been left out of the map and duration calculations. The urban alternate is commonly used when the peaks route is closed due to snow or fire restrictions. The urban route saves approximately 12.6 miles. Both options are selectable in the Alternate Route section above.

• Arizona Trail Association: The official organization managing the Arizona Trail. Includes passage-by-passage trail conditions, water reports, permit information, and thru-hiker resources.
• The Forrest Biome: Comprehensive web site discussing the AZT and Grand Canyon by local hiker, biker, science teacher and trail steward Forrest Radarian. Come here initially for a thorough discussion of important Grand Canyon and AZT logistics, which are as up-to-date and thorough as any you'll find elsewhere. But stick around for his writings on the beauty and joy of the Canyon.
• Grand Canyon Backcountry Permits: The Grand Canyon crossing is one of the most logistically complex sections of any National Scenic Trail. There are two small campsites set aside for AZT hikers (Bright Angel and Cottonwood), but permits are required for overnight camping at these sites and mustbe obtained in advance from the National Park Service. While a limited number of "Day Of" permits MIGHT be available, plan your crossing dates well in advance of your hike as permit availability is constrained at certain times of the year.