Firehole River
Yellowstone National Park
NW Wyoming, USA
Open live forecast →Target species: Brown and Rainbow.
Stream gauge: 06036905. Flow and water temperature update on every refresh.
Weekly AI Outlook as of 06/05/26
Firehole's running 289 cfs at 63°F — prime June conditions with PMDs and caddis both active in the warm geothermal water. This weekend's 70°F+ temps will drive strong midday hatches through the meadow sections, then Monday's cool front and rain should reset conditions nicely. Fish the indicator rigs Big Sky Anglers recommends (#16 Split Case PMDs, #16 OCD Caddis) until you see rises, then switch to dries. The geothermal influence keeps this river 2-3 weeks ahead of other Yellowstone waters.
- Flow: 289 cfs — excellent level for wade fishing the meadows below Old Faithful without crowding the fish
- Hatches: PMDs and caddis both firing with 63°F water temps. Expect midday emergence windows 11am-2pm this weekend
- Water Temp: 63°F from geothermal influence — warmest in Yellowstone system, triggering hatches weeks ahead of other rivers
- Best Window: Midday through late afternoon when air temps hit 70°F+ and drive surface activity in the meadow sections
Generated weekly from live USGS gauge readings, weather forecasts, and recent fly shop reports. Updates Friday mornings.
About this Water
- Freestone
- Best months: May–June and Sept–Oct (avoid hot summer months)
The Firehole River in central Yellowstone National Park is a thermal-influenced freestone — geothermal hot springs warm the river above optimal trout temperatures through mid-summer, creating an unusual seasonal fishery: excellent in spring and fall, often closed or unfishable in July and August due to thermal stress. Wild brown and rainbow trout dominate. The setting is extraordinary: river running through geyser basins, with steam from thermal features rising along the banks. Hatch sequences include caddis, PMD, and BWO through the cool months.
The Firehole is the only major trout river in the world running through an active geyser basin — anglers fish within sight of erupting geysers and steaming hot springs, a setting found nowhere else in fly fishing.
January Outlook
The Firehole River inside Yellowstone National Park is closed to fishing from November through the park's general opening. The geothermal-warmed water doesn't freeze but is protected during winter. The park provides limited winter access via snowcoach.
Productive Patterns
- Closed — YNP winter closure
Tips
The Firehole opens with the park's spring fishing season (varies by year — typically late May to early June). Winter visits to the park offer wolf watching near the Firehole corridor.
Water Notes
River closed. Geothermal heating keeps the river from freezing. YNP winter regulations apply.
February Outlook
Still closed. The Firehole Valley is prime winter wildlife habitat inside Yellowstone — bison, wolves, and otters frequent the geothermally-warmed banks. The river itself is not accessible for fishing.
Productive Patterns
- Closed — YNP winter closure
Tips
Visit the Firehole on a winter snowcoach tour for wildlife. The fishing season opens when the park opens in spring.
Water Notes
Closed. River ice-free due to geothermal input. Wildlife abundant on the warm riverside.
March Outlook
Still closed under YNP winter regulations. The Firehole Valley is spectacular in late winter with geothermal steam rising over the warm river in cold air. A world-class wildlife experience without the fishing.
Productive Patterns
- Closed — YNP winter closure
Tips
Late March occasionally sees early park opening. Check nps.gov/yell for current season opening dates.
Water Notes
Closed. Spring opening approaches. Check YNP website for current season start.
April Outlook
The park may open for fishing in late April in warm years — check current YNP regulations. The Firehole's geothermal character means it fishes differently than other rivers: the water can be too warm in summer but is uniquely productive in spring when thermal input warms the river while others are frigid.
Productive Patterns
- Pale Morning Dun
- Sparkle Dun #18
- RS2
- Soft Hackle
Tips
The Firehole's thermal heating can actually be an advantage in early spring — while the Madison or Gallatin are ice-cold, the Firehole is producing consistent hatches. If the park is open, this is a sleeper opportunity.
Water Notes
If open: 150–350 cfs. Water 54–62°F — warm for April. Variable with thermal input. Check YNP opening dates at nps.gov.
May Outlook
The Firehole in Yellowstone NP opens in late May. Geothermally warmed water produces early PMD and Caddis activity. One of the most unique rivers in the world.
Productive Patterns
- PMD Sparkle Dun
- Elk Hair Caddis
- Soft Hackle
- CDC Emerger
Tips
The Firehole's geothermal nature means it fishes differently than a freestone river. PMD hatches can begin in late May when nearby rivers are still cold. The 4-mile section from Midway Geyser Basin downstream is the most productive.
Water Notes
Low stable flows 200–500 cfs. Warm 56–65°F due to geothermal inputs. Unique thermal chemistry affects fly selection.
June Outlook
Excellent early season fishing with PMDs and Caddis. The Firehole often produces the best dry fly fishing in Yellowstone during June.
Productive Patterns
- PMD
- Elk Hair Caddis
- Baetis Sparkle Dun
- Soft Hackle
Tips
Fish the meander section through the meadows below Old Faithful. The geothermal warming produces hatches 2–3 weeks ahead of other Yellowstone rivers. The fish are wild, spooky, and require careful presentations.
Water Notes
200–500 cfs. Water 58–68°F — warmest in the Yellowstone system due to geothermal. Actually fishes best in spring and fall when temps are moderate.
July Outlook
The Firehole can become too warm in July for comfortable fishing during midday. Early morning and evening sessions are most productive.
Productive Patterns
- Hopper
- Elk Hair Caddis
- PMD Cripple
- Ant
Tips
Fish the early morning before temps peak. The river cools with canyon shade in the evening. Avoid midday when water temps exceed 70°F. Focus on the lower meadow section.
Water Notes
Low flows 150–350 cfs. Water temps can reach 70–75°F midday in July. Fish the cool-water hours.
August Outlook
The Firehole in August is typically too warm for quality fishing due to geothermal input. Water temperatures can exceed 78°F — above trout tolerance. The park closes portions of the Firehole when thermal stress is detected. Fish the Gibbon or Madison junction area instead.
Productive Patterns
- Avoid — thermal stress
Tips
The Firehole is the one river in Yellowstone that suffers from summer heat. Geothermal input pushes water temperatures into the lethal range for trout in August. Visit the Firehole for the scenery and explore the Madison or Lamar instead.
Water Notes
150–300 cfs. Water 72–80°F in August — stressful for trout. Portions may be closed by YNP when temps exceed thresholds.
September Outlook
The Firehole is at its best in September. Temps are perfect, PMD and Caddis activity is consistent, and the crowds have thinned.
Productive Patterns
- Blue Winged Olive
- PMD Cripple
- Elk Hair Caddis
- Soft Hackle
Tips
September is the Firehole's finest month — temperatures are ideal and the meander section is fishing at full capacity. Brown trout spawning preparation makes them aggressive.
Water Notes
Flows 200–450 cfs. Ideal water temps 60–68°F. Perfect September conditions on one of the world's most unique rivers.
October Outlook
Excellent October fishing. PMDs and Caddis continue and the river's geothermal heating keeps it productive late into fall.
Productive Patterns
- Blue Winged Olive
- Elk Hair Caddis
- Mahogany Dun
- Soft Hackle
Tips
October on the Firehole is exceptional — warm geothermal water keeps the river productive when surrounding streams are cold. BWO and Mahogany Dun hatches are reliable.
Water Notes
Flows 200–400 cfs. Water temps 58–65°F due to geothermal effect. Fish well into October when other rivers have slowed.
November Outlook
The Firehole closes with the Yellowstone season in early November. The geothermal corridor is beautiful in late fall as steam rises over the cooling landscape.
Productive Patterns
- Season closing by early November
Tips
Check current YNP season closing dates. Once closed, the Firehole corridor is accessible via snowshoe or snowcoach for wildlife viewing.
Water Notes
Season closing. River remains unfrozen due to geothermal input. YNP regulations apply.
December Outlook
Closed for the season inside Yellowstone National Park. The Firehole valley in December is accessible only via snowcoach or snowmobile from the West Yellowstone entrance.
Productive Patterns
- Closed — YNP winter season
Tips
Yellowstone's Firehole in winter is extraordinary wildlife habitat — wolves, bison, and geothermal features in snow. The river doesn't close until the park closes, but access requires a snowcoach or snowmobile permit.
Water Notes
Closed. Geothermal river ice-free but inaccessible without winter transport.
Hatch Calendar
| Insect | Peak | Active | Size | Productive Patterns |
|---|---|---|---|---|
| Blue Winged Olive Baetis tricaudatus |
May, Sep, Oct | Mar, Apr, May, Sep, Oct, Nov | #18–22 |
|
| Midge Chironomidae spp. |
Jan, Feb, Mar, Dec | Jan, Feb, Mar, Apr, Oct, Nov, Dec | #20–24 |
|
| Pale Morning Dun Ephemerella inermis |
Jun | May, Jun, Jul | #16–18 |
|
| Caddis Brachycentrus, Hydropsyche, Nectopsyche, Oecetis spp. |
Jun, Sep | May, Jun, Jul, Sep, Oct | #10–16 |
|
| Salmonfly Pteronarcys californica |
Jun | May, Jun | #4–8 |
|
| Yellow Sally Isoperla spp. |
Jun | Jun, Jul | #14–16 |
|
Access & Approach
Old Faithful, WY is the closest base. National park entry fee + Yellowstone fishing license required. Check current temperature-based closures before fishing in summer.
Nearby Fly Shops
- Blue Ribbon Flies
- Madison River Outfitters
- Big Sky Anglers
- Parks' Fly Shop
- Henry's Fork Anglers
- TroutHunt
Regulations & License
Fishing in Wyoming requires a current license. Always verify season dates, bag limits, and any special-regulation waters before you fish.
Wyoming fishing regulations & license →
Nearby Waters
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About Current
Firehole River conditions on Current combine real-time flow data (USGS, WSC, CDEC, CEHQ), weather, tide predictions, hatch probabilities calibrated to this specific water, and recent fly shop reports from the area.
Firehole River is one of 245 hand-curated waters in Current. The app and web forecast also generate AI outlooks for any unlisted river, lake, or saltwater flat anywhere in the world — drop a pin or paste a name and Current produces a fresh seasonal outlook with weather, flow context, and recommended techniques.
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