Heat Closures
Yes, South Mountain Park and Preserve stays open year-round, including summer. On days when the National Weather Service issues an Extreme Heat Warning, the City of Phoenix restricts four routes from 8 a.m. to 5 p.m.: the Holbert Trail, the Mormon Trail, the Hau'pal Loop Trail and access to the National Trail from the Pima Canyon Trailhead. More than 100 miles of other trails stay open. Separately, dogs are not allowed on any City trail when the temperature is above 100°F.
Heat Rules at a Glance
Which Trails Close on Extreme Heat Warning Days
- Holbert Trail — the main hiking route to Dobbins Lookout.
- Mormon Trail — the usual way to Hidden Valley and Fat Man's Pass.
- Hau'pal Loop Trail — 2.8 miles on the City map.
- National Trail from the Pima Canyon Trailhead. The National Trail stays open from other trailheads, and every other Pima Canyon trail stays open.
The City counts fewer than 7 miles of trail in the park subject to these restrictions. The restriction runs 8 a.m. to 5 p.m. only. Dobbins Lookout by car is not affected.
How the Program Started
- 2021: the Phoenix Parks and Recreation Board created the Trail Heat Safety Program to protect trail users and first responders from extreme heat.
- October 25, 2024: the Parks Board voted to expand the program to all trails at South Mountain and to start closures an hour earlier, 8 a.m. to 5 p.m.
- March 27, 2025: after public comment, the Board narrowed the South Mountain list to the routes above, effective immediately.
The City reports that in 2024, Phoenix had 45 days of trail closures for Extreme Heat Warnings between May 1 and October 13, 121 days at 105°F or higher and 69 days above 110°F. Rescues on closed trails fell from 57 in 2021 to 47 in 2022, 30 in 2023 and 35 in 2024.
Dogs and Heat
Phoenix City Code bans dogs from City trails when temperatures are above 100°F. The City also suggests testing the ground with your palm for 10 seconds: if it's too hot for your hand, it's too hot for paws. Dogs at South Mountain
How to Know Before You Go
- Email alerts: the City runs a mailing list for Extreme Heat Warning trail restrictions, linked from its Heat Safety page.
- Weather Service: a heat warning comes from the National Weather Service forecast for Phoenix.
- On any hot day: the City's checklist still applies. Start at first light, carry more water than you think you need, turn back before it runs out, carry a phone and hike with someone.
More than 200 hikers are rescued from Phoenix's desert and mountain parks every year, according to the City.
Heat Closures FAQ
Is South Mountain closed in the summer?
No. On Extreme Heat Warning days, the City restricts the Holbert, Mormon and Hau'pal Loop trails and National Trail access from Pima Canyon from 8 a.m. to 5 p.m. The rest of the park stays open.
What time do South Mountain trails close for heat?
From 8 a.m. to 5 p.m., only on days when the National Weather Service issues an Extreme Heat Warning.
Can I bring my dog to South Mountain in the summer?
Not when it's above 100°F. Phoenix City Code bans dogs from City trails at those temperatures.
Can I still drive to Dobbins Lookout during a heat warning?
The heat restrictions apply to trails, not to Summit Road. The park entrance keeps its normal 5 a.m. to 7 p.m. hours.