Trails of Tucson

Methods

How the hiking ratings are made

Trail ratings come from simple temperature cutoffs, not from AI and not from the NWS. The cutoffs below are our own, and no medical or heat-safety expert has reviewed them.

What a rating looks like

On a hot day, a rating might read: Lower heat exposure before 9am, skip from 10am (104F forecast at 1pm). Forecast updated 6:15am.

Each hour is rated by the air temperature or the feels-like temperature, whichever is higher, and the rating says when the feels-like number is the one that counts. Ratings stop at sunset, which is estimated for each trail with the NOAA method and can be off by a few minutes. Hours after sunset still show their temperatures.

A Heat Advisory, Extreme Heat Warning, Extreme Heat Watch, Flash Flood Watch, Flash Flood Advisory, or Flood Advisory is named in the rating, and while one is in effect the rating never calls an hour lower heat exposure. A Flash Flood Warning, Severe Thunderstorm Warning, or Dust Storm Warning means No rating. A Winter Storm Warning, Blizzard Warning, Ice Storm Warning, Extreme Cold Warning, Winter Weather Advisory, Winter Storm Watch, Extreme Cold Watch, Cold Weather Advisory, Freeze Warning, High Wind Warning, or Wind Advisory is named on any trail it covers. On the three high-elevation trails (Aspen, Marshall Gulch, and Butterfly), a Winter Storm Warning, Blizzard Warning, Ice Storm Warning, or Extreme Cold Warning means No rating instead.

A trail also shows No rating when our closure notes list it as closed, when today is one of its listed weekday closures and the order hasn't ended (a federal holiday stays open when that order says so), when forecast data is missing or more than 6 hours old, or when alerts couldn't be checked. If alerts couldn't be checked, the page says so instead of showing no alerts. Your browser also checks the forecast age when you open a page, and switches the ratings, the daily high, and the hourly labels to No rating once the weather data is more than 6 hours old. For a weekday closure, your browser works out today from the Phoenix date, and shows No rating when today is closed, or when the page was built on a closed day and today is open.

The forecast refreshes every 4 hours, overnight too, so it should only pass the 6-hour limit if an update fails. The Sabino Creek gauge reading is marked out of date when it is more than 2 hours older than the weather data on the page.

Shade, trail length, and water are listed when an official source gives them, and marked Not listed when it doesn't. They don't change the ratings. We don't model shade hour by hour.

Data sources

• NWS API, api.weather.gov: hourly forecast, forecast area elevation, feels-like temperature, and active alerts. Public domain. The ratings built from these numbers are ours, not an official NWS product. API documentation. NWS disclaimer.
• NWS HeatRisk, an experimental product. Every page that shows it says so. HeatRisk.
• USGS 3DEP elevation point service for pin elevation. EPQS.
• USGS Water Data, site 09484000, Sabino Creek near Tucson. Provisional. Gauge page.
• USFS recreation sites and trail lines, NPS public points of interest, USFS and Arizona State Parks pages cited on each trail. Federal work is public domain.
• U.S. Census Bureau geocoder for a few street addresses printed on agency pages.
• OpenStreetMap for the Brown Mountain and Yetman pins, and for those two route lines, kept apart from the agency lines. This file is derived from OpenStreetMap and is shared under the Open Database License (ODbL). Copyright OpenStreetMap contributors. https://www.openstreetmap.org/copyright

Maps

Most route lines are public-domain USFS or NPS trail data, simplified for the map. Brown Mountain and Yetman use OpenStreetMap lines under the ODbL, which are mapped by volunteers rather than surveyed by an agency. Sabino Canyon and Tumamoc Hill show only a pin, because we don't have a good source line for those routes yet. Each map caption names its source.

Questions

When does a trail show No rating?

When the forecast is missing or more than 6 hours old, when alerts couldn't be checked, when the trail is listed as closed, or during a Flash Flood Warning, Severe Thunderstorm Warning, or Dust Storm Warning. On Aspen, Marshall Gulch, and Butterfly, a Winter Storm Warning, Blizzard Warning, Ice Storm Warning, or Extreme Cold Warning also means No rating.

If alerts couldn't be checked, does that mean there are none?

No. The page tells you alerts couldn't be checked. Look at weather.gov before you go.

Do winter warnings change every trail the same way?

No. Every trail names any winter or cold alert that covers it. Only the high-elevation trails, Aspen, Marshall Gulch, and Butterfly, switch to No rating for a Winter Storm Warning, Blizzard Warning, Ice Storm Warning, or Extreme Cold Warning.

Still being checked

• Sabino Canyon, Water: The USFS visitor center recreation record says no drinking water is available. The Sabino fee station record says drinking water is available from faucets. The two records don't agree, so bring your own water.
• Sabino Canyon, Sun and shade: We don't have hour-by-hour shade information for this trail.
• Sabino Canyon, Distance and climb: We haven't found one official length for the canyon road walk.
• Sabino Canyon, Hours: The visitor center web page lists 8:00 a.m. to 4:30 p.m. Monday through Friday, closed federal holidays. A recreation-site record says the visitor center is open daily 8 a.m. to 4:30 p.m. Those are visitor center hours, which can differ from trail hours.
• Seven Falls (Bear Canyon Trail), Sun and shade: We don't have hour-by-hour shade information for this trail.
• Seven Falls (Bear Canyon Trail), Distance to Seven Falls: We haven't found an official one-way distance to Seven Falls.
• Phoneline Trail, Listed elevation: The Phoneline page lists elevation 3,700 feet. It does not say whether that is the start, a high point, or a typical point. The USGS elevation on this page is for the visitor center pin, which is lower. We haven't confirmed the 3,700 foot figure.
• Phoneline Trail, Sun and shade: USFS describes rocky slopes, steep drop-offs to the creek, and cliffs rising over 1,000 feet. We haven't confirmed hour-by-hour shade. The page says the trail can feel quite hot in summer.
• Finger Rock Trail pin: The pin is the end of the mapped trail line, not a surveyed parking spot. The March 2025 guide lists the trailhead address as 7119 N. Alvernon Way. The Census geocoder did not match that address. The USFS page says a 35-vehicle lot at the northern end of Alvernon Way, open sunrise to sunset.
• Finger Rock Trail, Sun and shade: The guide says the first mile meanders through a forest of saguaros. The trail page says bedrock sections beyond the spring are steep and exposed. We haven't confirmed hour-by-hour shade.
• Finger Rock Trail, Hours and pets: Parking lot open sunrise to sunset. No day-use parking fee on the trail page. Pets are prohibited in the bighorn sheep area. Off-trail travel more than 400 feet from the trail is prohibited in lambing season. The page says January 1 through April 30 in one place and April 15 in a bullet. We haven't confirmed which end date is right.
• Pima Canyon pin: The guide prints the trailhead address as 1598 E. Magee Rd. The pin is where the Census Bureau places that address, not a surveyed parking spot. The southern end of the USFS Pima Canyon #62 trail line is nearby (about 32.35340, -110.94782).
• Pima Canyon, Sun and shade: The guide says the first mile traverses the hillside, then the next three miles follow the creek into oak-studded grassland. We don't have hour-by-hour shade beyond that.
• Ventana Canyon pin: The pin is the end of the mapped trail line, not a surveyed parking lot. The March 2025 guide address is 6601 N. Resort Dr. The Census geocoder did not match that address.
• Ventana Canyon, Water: The March 2025 guide lists drinking water at the Pima Canyon and Finger Rock trailheads and does not list it for Ventana. The guide says the trail crosses the wash many times and names Maiden Pools at 2.5 miles.
• Ventana Canyon, Sun and shade: We don't have hour-by-hour shade information for this trail.
• Tumamoc Hill pin: The contact page prints 1675 W. Anklam Rd., Tucson, AZ 85745. The walk page says to park on the street along Anklam Road, not in hospital or clinic lots. The pin is placed from the street address, not at the gate itself.
• Tumamoc Hill, Sun and shade: The walk page says to take care to protect yourself from the sun, and to carry a flashlight in the dark. We haven't confirmed hour-by-hour shade.
• Romero Canyon pin: The map prints Catalina State Park, 11570 N. Oracle Rd., Tucson, AZ 85737, phone (520) 628-5798. The trailhead is inside the park, so the pin is the park address, not the trailhead itself. The forecast covers the same area either way.
• Romero Canyon, Water: The map says seasonal streamflow at the wash. Montrose Pools are usually dry. Romero Pools are farther up. Don't count on any of it for drinking water. We haven't confirmed drinking water at the trailhead.
• Romero Canyon, Sun and shade: We don't have hour-by-hour shade information for this trail.
• Romero Canyon, Access: USFS: the trailhead is inside Catalina State Park and the park charges an entrance fee. We haven't confirmed the fee amount. Dogs and bicycles are not allowed past Montrose Pools, per the 2026 park map.
• Wasson Peak (Hugh Norris Trail), Distance: The NPS hiking page describes a route that reaches Hugh Norris from Sendero Esperanza, then continues about 1.9 miles plus a 0.3 mile spur. That isn't the full distance from this trailhead.
• Wasson Peak (Hugh Norris Trail), Water: We haven't found an NPS note about water at this trailhead.
• Wasson Peak (Hugh Norris Trail), Sun and shade: We don't have hour-by-hour shade information for this trail.
• King Canyon, Distance: We haven't confirmed an official length. The NPS page we found was unclear about it.
• King Canyon, Water: Not listed
• King Canyon, Sun and shade: We don't have hour-by-hour shade information for this trail.
• Signal Hill, Distance: We haven't found an official length.
• Signal Hill, Water: Not listed
• Signal Hill, Sun and shade: We don't have hour-by-hour shade information for this trail.
• Douglas Spring, Water: The campground is named for a spring, but don't count on the spring for drinking water.
• Douglas Spring, Sun and shade: We don't have hour-by-hour shade information for this trail.
• Tanque Verde Ridge, Water: Not listed
• Tanque Verde Ridge, Sun and shade: NPS mentions views from the ridge, so expect open, sunny stretches. We don't have hour-by-hour shade.
• Cactus Forest Trail, Distance: Not listed
• Cactus Forest Trail, Water: Not listed
• Cactus Forest Trail, Sun and shade: We don't have hour-by-hour shade information for this trail.
• Aspen Trail, Sun and shade: USFS says the first half mile or so passes the bare granite walls of upper Sabino Canyon. The return on Marshall Gulch is described as a cool, shady canyon. We haven't confirmed hour-by-hour shade.
• Marshall Gulch, Sun and shade: The Aspen Trail page says the Marshall Gulch Trail leads down a cool, shady canyon. We haven't confirmed hour-by-hour shade.
• Butterfly Trail, Distance: The Butterfly page we checked on Oct 2, 2026 doesn't give a length.
• Butterfly Trail, Sun and shade: The upper Catalina Highway complex page describes a network of wooded trails in general. We don't have hour-by-hour shade for Butterfly.
• Madera Canyon Nature Trail, Water: The nature trail record says no water is available. A nearby Madera trailhead picnic record says drinking water is not at that site and is available at nearby campgrounds. Confirm which faucet is actually on before you rely on it.
• Madera Canyon Nature Trail, Distance: We haven't found an official length for the nature trail.
• Madera Canyon Nature Trail, Sun and shade: We don't have hour-by-hour shade information for this trail.
• Brown Mountain pin: Community map pin. Not an agency survey.
• Brown Mountain, Location pin: OpenStreetMap node 4710124718 is named Brown Mountain Trailhead. OpenStreetMap is mapped by volunteers, not surveyed by an agency.
• Brown Mountain, Land manager: We haven't linked an official land manager page for this trail yet.
• Brown Mountain, Water: Not listed
• Brown Mountain, Sun and shade: Not listed
• Brown Mountain, Distance and hours: Not listed
• Yetman Trail pin: Community map pin. Not an agency survey.
• Yetman Trail, Location pin: OpenStreetMap node 4203557980 is named Yetman Trailhead. OpenStreetMap is mapped by volunteers, not surveyed by an agency. The common trail name is the David Yetman Trail.
• Yetman Trail, Land manager: We haven't linked an official land manager page for this trail yet.
• Yetman Trail, Water: Not listed
• Yetman Trail, Sun and shade: Not listed
• Yetman Trail, Distance and hours: Not listed

Closure notes come from Coronado National Forest alerts, last read on Oct 2, 2026. They are updated by hand, not by an automatic feed, so they can fall behind. Park Service alerts aren't included, so check nps.gov for trails in Saguaro National Park.

We didn't use Pima County's GIS trailhead locations. The county says its GIS data isn't meant for site-specific decisions, and the terms for commercial reuse weren't clear.