Potomac Heritage Trail Weather Planner

This site reports both actual temperatures and apparent temperatures (heat index and wind chill, calculated using the Steadman methodology). The apparent temperature reflects how conditions actually feel to the body accounting for humidity and wind, and is the basis for the thermal comfort tiers shown in the BestStart! output. Detailed explanations of how heat index, wind chill, and the thermal comfort scoring system work are provided on the Florida Trail, New England Trail, and Appalachian Trail pages, respectively.

Specific issues on the various sections of the trail include:

• Southern Maryland (miles 0–217): Low elevation, high humidity coastal plain. Heat and humidity are the primary warm-season concerns; the region regularly sees apparent temperatures above 100 °F in July and August. Winters are mild but damp. Much of this section is on paved roads.
• Washington D.C. (miles 217–229 or 245): Urban environment with an urban heat island effect; apparent temperatures in summer can exceed the surrounding countryside. The DC River Trail runs close to the Potomac and Anacostia rivers, which moderate temperatures somewhat. The City Park Trail passes through the wooded Fort Circle parks, which offer more shade but more elevation change.
• C&O Canal Towpath (miles 229–414): Flat to gently rolling trail along the Potomac River floodplain. Hot and humid in summer, particularly in the lower sections near DC. The Paw Paw Tunnel area and upper sections near Cumberland, MD can see cooler temperatures and more variable conditions.
• Great Allegheny Passage (miles 414–486): Follows the Casselman River and the Youghiogheny River gorge. More moderate temperatures than the lowland sections; the gorge can trap cool air in morning and evening. Fall foliage is spectacular here in October.
• Laurel Highlands Hiking Trail (miles 486–553): The most rugged section of the PHT, crossing the Laurel Ridge at elevations approaching 3,000 feet. Temperatures are noticeably cooler than the lowland sections; snow is possible from November through March. Spring runoff can make stream crossings difficult in late winter and early spring.

The Potomac Heritage National Scenic Trail (PHT) stretches from the Chesapeake Bay (Maryland and Virginia) to Laurel Ridge, Pennsylvania, following the Potomac River corridor through southern Maryland, Washington D.C., the C&O Canal, and into the Appalachian highlands. Like some other National Scenic Trails the PHT is definitely a work in progress, with multiple routes on both Maryland and Virginia sides of the Potomac, and no "official" through-hike corridor. So it is less of a single continuous footpath than a network of existing trails, greenways, and road connections assembled into a through-hike route.

All that being said, as a hiker myself living less than a mile from the PHT, the idea of through-hiking it appeals to me. And there is a clean, continuous route from Point Lookout, MD and along the Maryland side of the Trail that connects directly to the Pennsylvania sections and eventual Laurel Highlands terminus. So TrailTemps models this route as the "Main" backbone and ignores the other sections for through-hike purposes, while still retaining them for weather planning purposes.

Trail centerline geometry is provided by the National Park Service via the Federal Trail Data Standards (FTDS) ArcGIS Feature Service for the Potomac Heritage National Scenic Trail. On-spine sections are shown as solid lines; Virginia and Eastern Continental Divide sections available only in the Weather Planner are shown as lighter, semi-transparent lines. For authoritative navigation, always consult the NPS and the Potomac Heritage Trail Association.

• Trail miles: Section miles within each named section are measured from the section’s eastern starting terminus (mile 0) to its western end. For through-hike planning, miles accumulate from Point Lookout, MD (mile 0) westward to Laurel Ridge, PA (mile ~553 or ~570 depending on the D.C. route chosen).
• Road segments (Southern Maryland): The Southern Maryland section is largely an on-road bicycle route (the Tidewater Potomac On-Road Bicycle Route), following paved roads and shared-use paths from Point Lookout northward to the Washington D.C. area. These road segments are part of the official designated trail and are shown on the map as a solid line using the same color as the off-road sections. Hikers planning this section should be aware of road conditions, traffic, and shoulder availability, which can vary significantly. Always consult current trail conditions before setting out.
• Virginia and Eastern Continental Divide sections: The PHT network includes sections in Northern Virginia, the Northern Neck of Virginia, and an Eastern Continental Divide Loop near the Pennsylvania border. These sections are shown on the map (at reduced opacity) and are available in the Weather Planner tool, but they are not part of the continuous through-hike spine used by the Duration Calculator and BestStart! tool. Many of these Virginia sections are still under development and may be disconnected from the main trail corridor. Hikers interested in these sections should consult the National Park Service and local trail associations for current conditions and connectivity.

• Potomac Heritage National Scenic Trail (NPS): Official NPS page with trail maps, section guides, conditions, and planning resources.
• C&O Canal National Historical Park (NPS): The 184.5-mile C&O Canal Towpath forms the longest single segment of the PHT. The NPS page includes current trail conditions, campsite reservations, and flood closure information.
• Allegheny Trail Alliance (GAP Trail): Manages the Great Allegheny Passage from Cumberland, MD to Pittsburgh, PA. Provides current conditions, trailhead locations, and shuttle information.
• Laurel Highlands Hiking Trail: The 70-mile Laurel Highlands Hiking Trail through southwestern Pennsylvania forms the western end of the PHT through-hike.