Firehole River Facts

Location:

The Firehole River is born at Madison Lake in the western portion of Yellowstone.  It flows north for 33 miles before joining with the Gibbon River to create the Madison River. 

The Firehole flows past some of the favorite attractions of Yellowstone National Park including Old Faithful and several geyser basins.  The Grand Loop Road and Old Faithful Road follow the Firehole for part of its journey. 

Features:

The Firehole River is one of the most unique rivers in the world.  Thermal features along its route add their mineral rich hot water to the river, creating a vibrantly beautiful and interesting river.  Water temperatures in the Firehole are much higher than most trout rivers, but for some reason trout thrive in the Firehole. 

Brook trout, browns and rainbows average 10-14 inches in the Firehole.  The river is born a cold mountain stream, like many others.  Hot water from geothermal features first enters the river in the Upper Geyser Basin.  In 30 miles, the Firehole River warms almost 30 degrees.  This warm water temperature facilitates year-round insect activity and trout growth.  The Firehole River mainly flows through flat prairie type terrain.  At one point the Firehole disappears down a canyon which offers some great fishing at its lower end.  The Firehole is a great dry fly river. 

It fishes best in June, slows to a stop during the summer and picks up again in September.  It is the first river to clear in the spring, the first to slow down in the summer, and the first to pick up again in the fall.  The Firehole River fishes best on overcast, stormy days. 

Seasonal Strategies:

The Firehole is the first river to clear in the spring.  Caddis and mayflies begin hatching in June, when the river fishes best.  Low-profile flies are a must on the Firehole.  PMDs and Baetis hatch in June with the PMDs staying until July. 

From July through mid to late August, the Firehole effectively shuts down.  The water warms enough that the trout move into the cooler tributaries.  Caddis and midges appear again in September, staying until the first frosts of late fall.  Insects on the Firehole shrink dramatically as the season progresses, so should your flies. 

Terrestrials hit their peak in late August and early September.  Use a slim, sparse hopper or small ant or beetle for the best results.  Fishing on the Firehole requires spring creek type tactics.  Stalking and hiding your profile are often necessary to catch these wary trout.  Small flies and long, thin tippets are needed. 

While it is easy to wade the Firehole River, it is often better to fish from shore.  The larger trout hang out near the undercut banks and weed lines.  Fishing from shore gives you less risk of spooking the fish. 

Special Regulations:

The Firehole River is fly-fishing only.  The Firehole River often closes in the summer due to high water temperatures.  Check our blog for the latest information regarding closures and regulations.

Access:

The Firehole River is accessible by the Grand Loop Road and several trailheads.  The best fishing often requires a hike, but it is worth it. 

Special Cautions:

Stay on designated paths when hiking in geothermal areas.  This area has a high bear density, observe all the usual precautions for hiking in bear country.