Extreme heat warning hits Phoenix, closing popular desert hiking trails

Early-season desert plans around Phoenix are shifting fast as the National Weather Service warns of 105 to 111 degree afternoons on Sunday and Monday, with Monday expected to be the hottest day. That is hot enough to change not just comfort levels but access: the City of Phoenix trail heat-safety program closes or restricts major hiking routes during extreme heat warnings, turning a casual sunrise-to-brunch outing into a logistics decision.

If your plan was Echo Canyon at Camelback Mountain Preserve, Piestewa Peak Summit, or a South Mountain traverse, the new rule is simple: do not treat the usual morning window as enough protection. On extreme heat warning days, the City of Phoenix restricts certain trails from 8 a.m. to 5 p.m., including Echo Canyon and Cholla at Camelback, the Piestewa Peak Summit trail and associated trails, and South Mountain routes such as Holbert Trail, Mormon Trail, Hau’pal Loop Trail, and access to the National Trail from the Pima Canyon Trailhead. The warning issued by the National Weather Service Phoenix office is in effect for the Phoenix metro area and parts of western Imperial County on Sunday and Monday.

The timing matters because this is not midsummer fatigue creeping in slowly. NWS Phoenix said April 2026 finished above normal for high, low, and mean temperature, and it ranked as the third warmest April on record for Phoenix. For visitors arriving for a layover, spring baseball, or a weekend in the Valley, that means a familiar shoulder-season assumption can fail fast: a 6 a.m. start may still leave too much exposure for open ridgelines, long climbs, and trailheads with little shade.

Meteorologist Alicia Ryan and local public safety messaging point to the same adjustment plan: stay hydrated, wear light clothing, and move back into air conditioning or shade whenever possible. If the plan was a long desert loop, shorten it. If the plan was a summit route, pick lower, shadier terrain instead. If the plan was to park once and hike through the afternoon, abandon that version entirely and treat the day as a short outing, not a full adventure.

The broader safety net is already open. The Maricopa County and MAG Heat Relief Network launched May 1 and will run through September 30, with free cooled spaces, cooling centers, respite sites, and hydration stations across the Valley. Phoenix also opened its 24/7 heat relief site for the third year in a row on May 1. The message from the desert is blunt: in Phoenix, spring hiking is already entering heat-season rules, and route choice, start time, and go-no-go calls now belong in the same conversation as water and trail maps.