Continental Divide Trail Weather Planner

At approximately 3,100 miles, the Continental Divide Trail is one of the longest and most challenging National Scenic Trails in the United States. Running from Antelope Wells, New Mexico 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 state include:

• New Mexico (miles 0–795): 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 800–1,525): The most technically challenging state, 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 1,530–2,300): 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 (miles 2,305–3,025): The coldest state and the one presenting the greatest risk of early-season snow at the northern end of the trail. The Anaconda Cutoff saves approximately 77 miles by bypassing the Anaconda Range; the Spotted Bear Route adds approximately 20 miles for a scenic detour through the Bob Marshall Wilderness.

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, −75 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, −77 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, +20.5 mi): A scenic alternate through the Bob Marshall Wilderness via the South Fork of the Flathead River. Adds approximately 20 miles compared to the main CDT corridor; taken for the scenery and wilderness experience, not to save time or distance.
• Rocky Mountain National Park — CDT Main Route (Colorado): The standard CDT route through Colorado passes through Rocky Mountain National Park via the North Inlet Trail and Tonahutu Creek Trail, meeting at Flattop Mountain (~12,324 ft) on the Continental Divide; approximately 40 miles of above-treeline hiking. The Western Bypass through Never Summer Wilderness (−25 mi) is the shorter alternate, staying on the main CDT spine and rejoining after RMNP. It avoids the park permit requirement and is a fine route in its own right, but misses the spectacular alpine scenery of the park. It should be noted that some sources differ on which is the "official" main route and which is the alternate, though for our purposes we used the designation provided on the US Forest Service map.

The trail centerline shown on this map is sourced from the USDA Forest Service official public ArcGIS feature service and OpenStreetMap (for the Gila, RMNP Loop, Anaconda, and Spotted Bear alternates). 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 is approximately 8 miles shorter 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: The CDT technically passes briefly through Idaho near Yellowstone. For weather planning purposes, these miles are grouped with Wyoming, as the terrain and climate are essentially continuous.
• 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.