Continental Divide Trail Weather Planner

At 3,040 miles by the Continental Divide Trail Coalition’s own mile markers, the Continental Divide Trail is one of the longest and most challenging National Scenic Trails in the United States. Running from the Crazy Cook Monument on the New Mexico–Mexico border to Waterton Lake on the U.S.-Canada border in Montana, it traverses five states and crosses some of the highest terrain of any long trail in the country, including numerous passes above 12,000 feet in Colorado.

Specific weather issues by region include:

• New Mexico (miles 0–794): The hottest and driest section of the CDT, with July and August bringing monsoon rains and dangerous afternoon lightning at elevation. The Gila River Route alternate traverses lower terrain and is generally cooler in summer but wetter during monsoon season.
• Colorado (miles 794–1,535): The most technically challenging region, with the most miles above treeline. Afternoon thunderstorms are a near-daily occurrence in July and August. Snow can fall in any month of the year at the highest passes.
• Wyoming (miles 1,535–2,047): Includes both the remote Wind River Range and the broad, arid Great Divide Basin. The Basin is hot and dry in summer with little shade or water. The Wind Rivers offer spectacular alpine terrain with significant snow risk in early season.
• Montana/Idaho (miles 2,047–2,406): The stretch where the trail runs the divide itself as the Idaho–Montana state line, west and north of Yellowstone. Exposed ridge walking with long dry stretches, and CDTC treats it as its own region rather than assigning it to either state.
• Montana (miles 2,406–3,040): The coldest region and the one presenting the greatest risk of early-season snow at the northern end of the trail, through the Bob Marshall Wilderness and Glacier National Park. The Anaconda Cutoff and the Spotted Bear Route both leave the main trail here.

Elevation correction: The CDT’s extreme elevation changes can differ significantly from the ERA5-Land climate grid resolution (~9 km). Temperature normals on this site apply an elevation correction to apparent temperatures: if the trail is more than 300 feet above the ERA5 grid point, apparent high temperatures are adjusted −3.5°F per 1,000 feet of difference, and apparent lows −2.0°F per 1,000 feet. This correction is most significant in Colorado, where grid elevation discrepancies of 2,000–4,000 feet are common on high passes.

Four alternate route options are modeled in this planner. All are at least 10 miles in length with meaningfully different weather profiles.

• Gila River Route (New Mexico, about −72 mi): The classic CDT alternate through the Gila Wilderness and Gila River canyon. Lower elevation than the main route; popular among hikers who want to experience the Gila’s unique riparian environment. Multiple river crossings make it impassable during high water.
• Anaconda Cutoff (Montana, about −95 mi): The most significant shortcut on the CDT, bypassing the Anaconda-Pintler Wilderness via a more direct route. Very popular among thru-hikers looking to save time; somewhat less scenic than the main route but still passes through beautiful Montana terrain.
• Spotted Bear Route (Montana, about −16 mi): An alternate through the Bob Marshall Wilderness down the Spotted Bear River to the South Fork of the Flathead, taken for the river country rather than to save time — though it does save distance, because the main CDT follows the divide across this stretch while the alternate cuts through the drainage.
• Rocky Mountain National Park — Tonahutu Creek Route (Colorado, −17.6 mi): The main CDT runs through Rocky Mountain National Park, over Flattop Mountain (~12,324 ft) on the Continental Divide, with a long stretch above treeline. The Tonahutu Creek Route is a shorter variant between Grand Lake and Big Meadows. Sources have differed on which line through this area is the main route: an older Forest Service layer carried only a western bypass connector, which made the bypass look like the spine and the park itself like a 40-mile alternate. This map now follows CDTC’s own routing, which puts the Primary Route through the park.

The trail centerline, its mile markers and its 126 sections are sourced from the Continental Divide Trail Coalition’s own published GIS. The Gila River, Anaconda Cutoff and Spotted Bear alternates are not carried in CDTC’s data and come from OpenStreetMap, so their geometry and mileage are less reliable than the main trail’s. Both ends of each one are checked against the main trail at build time, and each currently meets it within a fifth of a mile. The northern terminus options (Waterton Lake and Chief Mountain) are both modeled; the direction selector above controls which terminus is used for duration calculations.

• Chief Mountain Terminus: The Chief Mountain border crossing at the eastern edge of Glacier National Park leaves the main trail near Many Glacier and runs 27 miles to the border, about 9 miles shorter overall than the official Waterton Lake terminus and avoids the international border crossing. It is a legal U.S.-only terminus option and popular among hikers who wish to avoid the Canadian entry process.
• Idaho: For roughly 360 miles west and north of Yellowstone the trail follows the divide where it is also the Idaho–Montana state line, crossing between the two repeatedly. CDTC groups these miles as a single “Montana/Idaho” region and this map follows that; each individual trail point is still labelled with the state it actually falls in.
• Current Conditions: Always consult the Continental Divide Trail Coalition (CDTC) and FarOut for current trail conditions, closures, and recent reroutes before your hike.

• Continental Divide Trail Coalition (CDTC): The primary stewardship organization for the CDT. Includes section guides, permit information, trail conditions, resupply resources, and detailed maps for trip planning.
• Colorado Avalanche Information Center: State government source of avalanche and snowpack information for Colorado, which has the highest and most snow-prone terrain on the CDT.
• NPS Continental Divide National Scenic Trail: The National Park Service page for the trail, with overview information, maps, and management contacts.
• USDA Forest Service: Most of the CDT passes through National Forest lands. The Forest Service manages permits, fire restrictions, and closures for these sections.