Sep 2, 2026

Dogs in the McDowell Sonoran Preserve: The 90-Degree Rule

Ninety degrees at any point in the hike, a leash that has to be in your hand, and a waste rule that bans the bag-and-collect plan. Scottsdale's Preserve rules, quoted.

Luis ZamoraCo-founder of PetCompass; Dog Dad to Banzo and Tuck

Scottsdale, Arizona11 min readThings to DoPet Care & Services

Scottsdale's threshold for hiking with a dog is 90 degrees. Phoenix's is 100. Ten degrees is the difference between the two cities, and in this climate ten degrees is most of the year.

Verbatim from the city's Preserve page, where the sentence is split across two lines on the page itself:

"If it is over" "90 degrees at any time in your hike, it's too hot for your dog."

"At any time in your hike." Not the temperature when you set off. The temperature at any point in the outing, which on a desert trail means the temperature when you are furthest from the car.

The city puts it plainer elsewhere on the same page, verbatim: "Check the hourly weather forecast BEFORE bringing your dog to the Preserve. If it will be more than 90 degrees during your outing, leave your dog at home." The capitals on BEFORE are the city's.

The four Preserve dog rules

Verbatim, in full, with the page's own line breaks:

"Dogs in the Preserve are a privilege. If you bring your dog, it is your responsibility to follow the rules:" "Dogs must be on handheld leash, no longer than six (6) feet at all times." "Waste must be pick up immediately and disposed of in a trash container or carried with you until" "you reach a trash container." "Loose or bagged waste on the trail is prohibited."

The "Waste must be pick up" grammar is as published.

Three things in there are stricter than the standard version of these rules.

"Handheld leash." Not just a six-foot lead, a six-foot lead in your hand. On the face of it that rules out clipping the lead to a pack, a belt or a waist runner's harness. If you hike hands-free elsewhere, this is the rule to change.

"Loose or bagged waste on the trail is prohibited." A bag left beside the trail to collect on the way back is a violation, not a plan. Carry it.

"A privilege." The city's framing, and it signals how it thinks about the permission.

Why 90 and not 100

Because of the ground, and Scottsdale publishes its own arithmetic.

From the Preserve's dog heat panel, verbatim: "Sidewalk/natural rock surface can radiate very high temps" and "90 degree atmospheric temp/ potential surface temp of 135 degrees".

90 degrees of air, 135 degrees of rock.

That figure does not line up with Maricopa County's, and both are government sources for the same metro area. The county's pet heat safety page publishes an asphalt table that puts 135 degrees at 86 degrees of air temperature and 143 degrees at 87. Different surfaces, different methods, and the numbers do not agree.

We are not going to reconcile them for you. Both say the same thing in practice: the surface is far hotter than the air, and it gets there earlier than you think.

The county's test is the one to carry, verbatim: "Place your bare foot or the back of your hand on the pavement for 7 seconds, if it's too hot for you, it's too hot for pets too!" Do it at the trailhead, on the rock, before you commit to a route.

The warning the city attaches to all of this

Verbatim from the Preserve page:

"For your safety, please check the weather forecast and take necessary precautions before choosing to enter the Preserve. And please be especially aware if you plan to bring your dog. The desert heat can kill them with little or no warning, and you could be charged with animal cruelty under State law."

"You could be charged with animal cruelty under State law." That is unusually direct language for a parks page, and it is the reason to treat the 90-degree line as a rule rather than a suggestion even though it is written as guidance.

The general heat panel on the same page lists "Leave pets at home" as one of its bullets, and separately says, verbatim: "PLEASE leave your dog at home; they cannot regulate heat effectively."

And the seasonal reality, verbatim: "Starting in May to about September, we will be experiencing triple digit temperatures almost every day."

May to September, the Preserve is not a dog destination. That is the honest summary.

The water rule, which is a turnaround rule

Verbatim: "Bring ample water for you and your dog. When it is half gone, turn around."

Half gone, turn around. It is the most useful single instruction on the page, because it converts a vague worry into a decision point. And note it applies to the shared supply: you are carrying water for two.

Scottsdale also suggests kit, verbatim: "Cool vests and trail booties for dogs are available and are very efficient."

Hours: the gates run on sunrise and sunset

The Preserve is, verbatim, "open everyday, sunrise to sunset, free of charge ." The stray space is the page's.

Verbatim: "Visit the Preserve early in the day. Gates open roughly 30 minutes before sunrise."

The city publishes an exact table of gate times by date. A selection, which is what a dog owner actually needs, because it tells you how early you can start:

Date	Open	Close
Jan. 1	7:02 a.m.	5:31 p.m.
April 1	5:45 a.m.	6:49 p.m.
May 1	5:09 a.m.	7:11 p.m.
June 15	4:47 a.m.	7:39 p.m.
Aug. 1	5:11 a.m.	7:27 p.m.
Oct. 1	5:52 a.m.	6:11 p.m.
Dec. 1	6:44 a.m.	5:20 p.m.

The earliest gates of the year are in mid-June, at 4:47 a.m. Which is exactly when you want them, and still not early enough to make a long summer hike sensible with a dog.

The table also carries a row reading "Noon on July 4" straight after the July 1 row. It has no column heading, so we read it as an early closure on Independence Day and we are labelling that as our reading rather than the city's statement.

The trap in the good weather

The Preserve's own rattlesnake page sets the season, verbatim:

"When temperatures are between 60°F and 90°F, the cold-blooded reptiles of the Preserve will emerge from hibernation; this includes rattlesnakes. Rattlesnakes are an important part of the Preserve ecosystem and are a protected species."

Read that range against the dog rule. Below 90 degrees is when it is cool enough to bring the dog. Sixty to 90 degrees is when the snakes are out. The good dog weather is the snake weather, and there is no month that avoids both problems.

The avoidance list includes the leash rule again, verbatim: "Always keep your dog(s) on a leash" and "Travel only on designated and posted trails" and "DO NOT TRAVEL OFF TRAIL".

Our rattlesnake bites and dogs in Scottsdale guide covers the clinic list the city publishes for exactly this, including which clinics hold anti-venom and which say they do not.

Heat first aid, and a conflict you should know about

Scottsdale and Maricopa County give different instructions, and we are printing both.

Scottsdale's Preserve page says, verbatim: "Immediate cooling of body with water, cool packs to groin, where legs meet the body, neck" / "Remove from heat immediately" / "Get to Veterinarian (Consequences of heat emergency = kidney failure, heart irregularities, other system failures, death)".

Maricopa County says, verbatim: "Do not attempt to rapidly cool pet with water or ice; this may cause shock" and "Do not force water".

Two government sources for the same metro area, giving opposite advice on water. We are not picking a winner. What both agree on: get the dog out of the heat immediately, and get to a vet. Call the hospital while you are moving and do what the vet on the phone tells you, because they will ask questions neither page can anticipate.

The warning signs, verbatim from Scottsdale: "Begins with heavy panting/signs of difficulty breathing" / "Tongue/gums appears bright red with thick saliva" / "Skin elasticity (when pinched, does not snap back)" / "Worsens if dog vomits, becomes unsteady, lethargic, unwilling to move (Core temp in the 104 degree range)". And for heat stroke: "lips/membranes become blue/gray" / "Rapid on-set collapse, seizure, unconsciousness and death".

On risk groups, verbatim: "The risk groups are much the same as humans: old, obese, suffer from medical conditions or take medicine. Certain breeds are more susceptible to heat emergencies than other breeds. These breeds with a broad, short skull: Boxers, Bulldogs, Pugs, etc."

And on the mechanism, verbatim: "Dogs do not actually sweat. They exchange heat through panting and to a minor degree, through their feet" pads, and the city adds that dogs do not tolerate high environmental temperatures as well as humans do.

One item on the city's list of causes we are paraphrasing rather than quoting, because the word it uses is one our house style does not print: it names higher temperatures arising from the air temperature combined with contact with a hot surface. Everything else on that list is verbatim above.

Our summer heat safety for pets and pet first aid basics guides cover the physiology, and our emergency vets in Scottsdale guide has the 24-hour hospitals.

The scale of the place, which is part of the risk

Verbatim: "The McDowell Sonoran Preserve is one of the largest permanently protected urban desert preserves in the world, encompassing more than 30,500 acres and over 230 miles of multi-use trails for hikers, bikers, and equestrians."

Thirty thousand acres and 230 miles of trail. It is easy to be two miles from a road here, and the consequence is that a dog that overheats or gets bitten has to be carried out.

The trails are also shared with bikes and horses, which is its own reason the handheld six-foot rule exists.

And one major trailhead is shut. Verbatim from the Brown's Ranch improvements page: "For your safety, Brown's Ranch trailhead and parking lot will be closed while undergoing improvements. During this time, there will be no parking on streets or in nearby neighborhoods allowed." The city gives an expected start date of July 13, 2026 and an expected completion of Fall 2026.

Its listed alternatives matter more to a dog walker than to anyone else, verbatim: "Tom's Thumb (no drinking water)" / "Pima-Dynamite" / "Fraesfield (no drinking water)" / "Granite Mountain (no drinking water)".

Three of the four have no drinking water. So the half-gone rule gets stricter, because there is nothing to top up from at the trailhead either.

A seasonal plan that works

November to March. Preserve season. Gates from about 6 a.m. to 7 a.m., temperatures below 90 most days, and the best dog hiking in the metro area. Go often, watch for snakes anyway on the warmer days.

April and October. Check the hourly forecast, not the daily high. The 90-degree line gets crossed in both months, and it is the temperature during your outing that matters.

May to September. Assume the answer is no. Dog parks at dawn instead, which is what our Scottsdale dog parks guide is for, and water play at home, which is what Maricopa County recommends.

Every trip, whatever the month. Water for two and the half-gone rule. Seven seconds on the rock at the trailhead. Lead in your hand. And a plan for waste that involves carrying it.

If you are visiting to hike with a dog, come in winter. Our pet-friendly hotels in Phoenix roundup and Phoenix hotel directory are the nearest PetCompass listings, and our road trip with your dog checklist covers the drive.

Frequently asked questions

Are dogs allowed in the McDowell Sonoran Preserve? Yes, on a handheld leash no longer than six feet at all times. The city describes dogs in the Preserve as a privilege and sets out four rules covering the leash, the heat threshold and waste.

What temperature is too hot to hike with a dog in Scottsdale? Over 90 degrees at any time during the hike, per the city. It advises checking the hourly forecast before you go and leaving the dog at home if it will be more than 90 degrees during your outing.

How is that different from Phoenix? Phoenix prohibits dogs on all city hiking trails at 100 degrees or warmer. Scottsdale's Preserve threshold is 90 degrees and is written as guidance rather than a prohibition.

What are the Preserve hours? Sunrise to sunset, free of charge, with gates opening roughly 30 minutes before sunrise. The city publishes an exact table by date, ranging from a 7:02 a.m. opening on 1 January to 4:47 a.m. on 15 June.

Can I hike hands-free with my dog in the Preserve? The rule states that dogs must be on a handheld leash no longer than six feet at all times, which on its face rules out clipping the lead to a pack or belt.

Can I leave a waste bag on the trail and collect it later? No. The city states that loose or bagged waste on the trail is prohibited, and that waste must be disposed of in a trash container or carried with you until you reach one.

Sources

Trail conditions, gate hours and closures change. Check the city's pages and the trailhead signage before you go.