Firehole River Wyoming - Yellowstone National Park Hatch Chart
Yellowstone National Park, Wyoming. The Firehole River is one of the most extraordinary trout streams in the world - a geothermally heated river flowing through the Upper, Midway, and Lower Geyser Basins past Old Faithful and Midway Geyser before joining the Gibbon River to form the Madison. No other trout river on earth runs through an active geyser basin. The combination of geothermal heating, exceptional insect life, and wild brown and rainbow trout in a setting unlike anything else in fly fishing makes the Firehole a singular destination.
A Yellowstone National Park fishing permit is required. The Firehole opens with the general park season - typically the Saturday of Memorial Day weekend - and closes in early November. Sections of the river have special regulations including catch-and-release requirements. Obtain current regulations from the National Park Service before fishing. The park entrance fee applies year-round.
Shop by type: dry flies, nymphs, Euro nymphs, hoppers and terrestrials.
The river
The Firehole flows approximately 20 miles from its headwaters near Old Faithful north to its confluence with the Gibbon at Madison Junction. The upper river through the geyser basins is the most iconic water - meadow character with slow, clear flows past steaming thermal features, bison on the banks, and wild trout rising in improbable surroundings. The lower river through Firehole Canyon has faster pocket water and a more conventional freestone character, with excellent brown trout populations and fewer visitors than the famous meadow sections.
Brown trout are the primary species with rainbow trout present throughout. Both species are wild, unhatchery-influenced fish that have adapted to the unusual thermal conditions of the river. The geothermal inputs keep the Firehole warmer than surrounding freestone streams in spring and fall, producing early season insect activity and extending the hatch season at both ends. In midsummer, however, the same geothermal heating pushes water temperatures above trout comfort levels - the Firehole typically closes to fishing in August due to thermal stress on the fish, reopening when temperatures drop in September.
The Firehole's PMD hatch is legendary - one of the finest in Wyoming and perhaps the finest in Yellowstone National Park. The meadow sections in late June and July produce dense PMD hatches with large, selective rising trout in spectacular geyser basin scenery. This is the Firehole at its most celebrated and most demanding.
Year at a glance
| Month | Primary hatches | Also carry | Typical sizes |
|---|---|---|---|
| Jan - Apr | Closed (park season) | - | - |
| May | BWO, midges, caddis start | Small nymphs | BWO 16-20, midge 20-24 |
| Jun | PMD, caddis, BWO | Yellow sally, midges | PMD 16-18, caddis 14-16 |
| Jul | PMD, caddis, hoppers start | Yellow sally, ants, midges | PMD 16-18, caddis 14-16 |
| Aug | Closed - thermal stress | - | - |
| Sep | BWO, caddis, hoppers | Mahogany dun, midges | BWO 16-20, hopper 8-12 |
| Oct | BWO, midges | Mahogany dun | BWO 16-20, midge 20-24 |
| Nov | Closes early November | - | - |
May - Opening season
The Firehole opens with the general park season on the Saturday of Memorial Day weekend. The geothermal heating gives the Firehole an advantage over surrounding park streams in May - hatches begin earlier and fish are more active in the warmer water. BWO hatch well on overcast afternoons from opening day. Midges throughout. Caddis begin building by late May. The meadow sections above and below Old Faithful are beautiful in May with minimal summer crowds and excellent early-season fishing.
- BWO - 16-20. Parachute BWO and CDC Baetis emerger on overcast afternoons.
- Midges - 20-24. Red zebra midge subsurface throughout.
- Late May: first caddis - 14-16 on warm afternoons. Elk hair caddis.
- Small nymphs in the deeper meadow runs. Nymphs.
June
June is the beginning of the Firehole's finest season. PMDs begin hatching in the meadow sections and quickly become the dominant event - the combination of the geyser basin setting, rising wild browns and rainbows, and dense PMD hatches makes June on the Firehole one of Yellowstone's most sought-after fly fishing experiences. Caddis evenings are excellent throughout the month. BWO continue on overcast days. Yellow sallies in the faster Firehole Canyon sections. The river is at ideal fishing temperatures in June - come before the July heat pushes temperatures up.
- PMD - 16-18. Pale Morning Dun mornings and midday in the meadow sections. The signature hatch.
- Caddis - 14-16 evenings. Elk hair.
- BWO on overcast days. Parachute BWO.
- Yellow sally - 14-16 in the Firehole Canyon riffles on warm afternoons.
- Midges throughout. Red zebra midge subsurface.
July - early
PMDs continue through early July in the cooler morning hours and the Firehole meadow fishing remains outstanding. Caddis evenings. Hoppers begin appearing along the meadow margins. The Firehole's geothermal heating becomes a liability as July progresses - water temperatures rise above comfortable trout levels in the afternoon heat. Fish early morning and evening in July. The National Park Service monitors temperatures and closes the Firehole when thermal stress thresholds are reached - typically by mid to late July. Check current closure status before making the drive.
- PMD - 16-18. Pale Morning Dun mornings. Fish early before temperatures rise.
- Caddis - 14-16 evenings when temperatures drop. Elk hair.
- Hoppers beginning - hoppers and terrestrials along the meadow margins.
- Yellow sally - 14-16 in the canyon sections.
- Ants and beetles midday from hoppers and terrestrials.
August - thermal closure
The Firehole is typically closed to fishing through most of August due to thermal stress on the fish. The National Park Service closes the river when temperatures exceed safe levels for trout - this closure protects the wild fish population and is strictly enforced. Check the NPS Yellowstone fishing regulations page for current closure status and reopening dates. The Gibbon, Madison, and other park streams remain open during the Firehole closure and offer alternative fishing during this period.
- The Firehole is closed to fishing in August in most years. Check current NPS closure status before visiting.
- Alternative park streams during the Firehole closure: the Madison River in Yellowstone National Park remains open and fishes well in August.
September
The Firehole reopens in September when temperatures drop to safe levels - typically in the first two weeks of the month - and September is arguably the finest month on the river. The summer crowds are gone, the geothermal setting is at its most dramatic with cool morning air and steaming thermal features, BWO return strongly, hoppers continue through mid-month, and the wild trout have rested through the August closure. The fall Firehole is the river at its most uncrowded and most beautiful. Check the reopening date before planning your trip.
- BWO - 16-20. Parachute BWO and CDC Baetis emerger on overcast afternoons. Outstanding fall olive fishing.
- Hoppers through mid-September. Hoppers and terrestrials along the meadow margins.
- Mahogany dun - 14-16 on overcast afternoons.
- Caddis evenings. Elk hair.
- Midges building. Red zebra midge subsurface.
October - early November
BWO and midges dominate the fall season through October. The Firehole's geothermal heating extends the season compared to surrounding freestone streams and the river fishes well into October with excellent BWO hatches and minimal pressure. Mahogany duns on overcast days. The river closes in early November - check current NPS regulations for exact closing dates. October on the Firehole with steam rising from the geyser features, fall colors on the meadow margins, and large wild browns rising to BWO is one of the most memorable experiences in Yellowstone fly fishing.
- BWO - 16-20. The dominant hatch. Parachute BWO.
- Mahogany dun - 14-16 on overcast afternoons.
- Midges - 20-24 throughout. Red zebra midge subsurface.
- Season closes early November - check NPS regulations for exact date.
A western dry and nymph assortment covers the core season. The Firehole does not require an extensive box - PMDs, BWO, caddis, and midges cover most situations. Bring 5X tippet as the meadow fish can be selective. The Firehole River is unlike any other trout stream on earth - fish it at least once. June for PMDs, September for fall BWO and complete solitude.