Ontario Peak Hiking Guide
Ontario Peak rises above the Cucamonga Wilderness in the San Gabriel Mountains, delivering one of the most rewarding summit panoramas in the entire Inland Empire. The 12-mile out-and-back route gains nearly 3,900 feet through dense forest, open chaparral, and a dramatic alpine ridge before topping out at approximately 8,693 feet. Dogs are not permitted in the Cucamonga Wilderness, and a day-use permit is required for entry. Come prepared for a full-day effort — this trail earns its strenuous rating at every switchback.
Permit: Cucamonga Wilderness day-use permit required; self-issue permits are typically available at the trailhead register, but check current Angeles National Forest regulations before your trip as requirements can change.
Trail Overview and Route Description.
The standard route to Ontario Peak begins at the Icehouse Canyon Trailhead in Mt Baldy Village. Hikers follow Icehouse Canyon Trail through a shaded canyon lined with cedar and pine before the grade steepens sharply toward Icehouse Saddle at approximately 7,600 feet. From the saddle, the trail branches; bear right toward Ontario Peak and follow the ridge as it climbs through exposed alpine terrain. The final push to the summit involves a well-worn use trail over rocky ground. The total distance is 12 miles round trip, making pacing and water management critical considerations for this route.
Permit and Wilderness Regulations.
Entering the Cucamonga Wilderness requires a free day-use permit. Self-issue permits are generally available at the Icehouse Canyon Trailhead register, but availability and procedures are subject to change under current Angeles National Forest management. Check the Angeles National Forest website or contact the Mt Baldy Visitor Center for the most up-to-date requirements before your visit. Campfire regulations are strict in this wilderness area, and open fires are often prohibited during fire season. Pack out all waste, stay on designated trails, and respect Leave No Trace principles throughout.
Elevation Profile and Difficulty.
With 3,900 feet of elevation gain packed into roughly 6 miles of uphill travel, Ontario Peak demands a strong aerobic base and solid leg strength. The lower Icehouse Canyon section is relentlessly uphill but partially shaded, offering some relief on warm days. The terrain shifts above the treeline where the ridge becomes more exposed and rocky. Altitude can affect hikers unaccustomed to elevations above 8,000 feet, causing fatigue or mild headaches. Budget at least 6 to 8 hours for the round trip at a moderate pace, and do not underestimate the return descent, which punishes tired knees on loose trail surface.
Summit Views and What to Expect at the Top.
The Ontario Peak summit offers a 360-degree panorama that justifies every hard-earned foot of gain. On clear days — most common in spring and after autumn cold fronts — you can see across the entire Los Angeles Basin, the Inland Empire sprawl, the Santa Ana Mountains to the south, and neighboring San Gabriel peaks to the north and east. The summit area is rocky and wind-exposed, so bring an extra layer even in summer. Nearby Cucamonga Peak is visible along the ridge and draws equally strong views, making it a natural landmark for orientation at the top.
Best Seasons and Conditions
Spring brings wildflowers in the lower canyon and reliable water flow in Icehouse Creek, making it the most scenic season for this hike. Summer mornings offer manageable temperatures before afternoon heat builds at lower elevations, but the high ridge can develop thunderstorms by early afternoon — start before dawn to be off the exposed summit by noon. Fall delivers crisp air, excellent visibility, and golden foliage in the canyon, arguably the best overall conditions on this trail. Winter is not recommended for most hikers, as snow and ice on the upper ridge require microspikes or crampons and significantly increase the risk of injury.
Water, Gear, and Safety Essentials.
Icehouse Creek provides seasonal water in the lower canyon that can be filtered, but do not rely on it during dry years or late summer. Carry at least 3 liters from the trailhead. The exposed ridge above 7,500 feet offers no shade and no water sources. Essential gear includes a trail map or downloaded offline GPS route, sun protection, trekking poles for the descent, and layers for the summit. Cell service is unreliable on the upper mountain. Tell someone your planned return time, and consider hiking with at least one other person given the remote wilderness setting and length of the route.
Hiking tips for Ontario Peak
- Start by 6 a.m. to beat afternoon thunderstorms on the exposed summit ridge and to secure trailhead parking, which fills quickly on weekends.
- Pick up your Cucamonga Wilderness permit at the Icehouse Canyon Trailhead register before stepping onto the trail — rangers do patrol this area.
- Trekking poles make a significant difference on the steep, loose descent from the summit back to the saddle; pack them even if you rarely use them.
- Layers are non-negotiable: the canyon trailhead can feel warm while the ridge summit sits 20 or more degrees cooler and remains wind-exposed all year.
- Dogs are prohibited in the Cucamonga Wilderness — leave your pets at home and plan a dog-friendly trail for a separate outing.
Nearby trails to explore
- Cucamonga Peak Trail
- Telegraph Canyon Trail
- Icehouse Canyon to Icehouse Saddle.
Hike this trail with TrailMates
Tackling a strenuous wilderness route like Ontario Peak is safer and more rewarding with the right group behind you. Use TrailMates to find Inland Empire hikers who match your pace and skill level, coordinate a summit attempt with the app's group planning tools, and take advantage of the 3-person minimum meetup feature designed to keep everyone safer on remote trails like this one.