Freestone · Mixed · Wyoming

Firehole River

Two anglers casting fly rods while wading the Firehole River at golden hour, Yellowstone National Park.

The Firehole is a strange, lovely meadow river that slides past geysers and hot springs inside Yellowstone NP, holding browns and rainbows in some of the oddest country a trout ever lived in.

Poor · Rainbow Trout
Parachute Adams · 12-18
Poorlive now
Not the day for it
River steady at a fishable height. Not much stacked in your favour today. Worth an hour if you are nearby, not worth the special trip.
90% confidence
What moved it
  • Level0.91 mLast reading 14h ago
  • Water temp23.1°C
  • ClarityClear
Today's fly
Parachute Adams
Parachute Adams12-18
High-confidence seasonal pick
Conditions on the water
Live gauge
Level
Steady
0.91 m
Last reading 14h ago
Water temp23.1°C
ClarityClear
Weather13°C
WindS 4 km/h
Pressure1019 hPa
Rain · recent0.0 mm
Rain · ahead0.0 mm

Live readings only. Trends shown where the gauge supports them.

Water temperature for Rainbow Trout
Warm — slow
23.1°Cideal 1018°C
0°14°28°
How to fish it · for Rainbow Trout
When
Nymphing can work through most of the day.
Where
Cover mixed depths.
Method
Start with tight-line nymphs and adjust if fish rise or drift higher.
Kit
9 ft #4 rod, floating line, 12 ft tapered leader to 4–5 lb fluoro tippet.
Why this works
Water at 23.1°C. This is the line where catch-and-release kills brown trout. Do not fish for them today.
Sub-surface · on the nymphunder the surface

Hatch predictions

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Beyond the hatch · worth watchingambient prey

Hatch predictions

Top prey shown — see all 2 with Pro.

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Evidence
ModelledModerate confidence

Modelled from regional ecology — no survey or occurrence data for this water yet.

Through the year
0–3 scale · July highlighted
J
F
M
A
M
J
J
A
S
O
N
D
Western Green DrakeHatch
2
2
Flav (Small Western Green Drake)Hatch
2
3
2
Mahogany DunHatch
2
2
American March BrownHatch
2
3
2

Numbers are intensity 0 (none) to 3 (peak) — a guide, not a guarantee.

Ranked for today
Rainbow Trout fly box
Permits & access
Permit required — see local rules.
  • Yellowstone NP licence and special regulations
  • Geothermal input pushes summer water temperatures too high to fish ethically — it is a spring and autumn river.
What's coming
Plan ahead
5-day outlook
Water here at 23.1°C. Nothing cooler within range.
Gallery · 2
  1. Two anglers casting fly rods while wading the Firehole River at golden hour, Yellowstone National Park.
    Visitors fishing the Firehole River
  2. Terrain map of the venue
    Terrain map
About this water

The Firehole is a strange, lovely meadow river that slides past geysers and hot springs inside Yellowstone NP, holding browns and rainbows in some of the oddest country a trout ever lived in. It's a spring and autumn river by necessity — all that geothermal water shoves summer temperatures too high to fish in good conscience, so you leave it alone in the heat. Park special regulations apply. Swing a soft-hackle through the geyser-basin flats in the cool months and let high summer belong to the river.

Under the surface

The Firehole is the strangest trout river in America, and possibly the most beautiful. It runs through the heart of Yellowstone's geyser country, and the hot water of the basins — Old Faithful, Midway, the Lower Geyser Basin — bleeds into it until the river is literally warmed by the earth. Steam drifts off the meadows; the bank may be a bubbling spring. The result is a smooth, clear, weed-rich meadow stream that fishes early and late in the season when other rivers run too cold, and shuts down in midsummer when the geyser heat pushes it too warm for the trout's comfort. The bed is volcanic sand and gravel over rhyolite. The browns and rainbows here are wild and well-educated. Wading is easy on firm footing — but mind the thermal ground at the edges, which is exactly as dangerous as it looks.

Wading: Scalding thermal ground at the banks

  • Mixed
  • Unconfined
  • Pool riffle
The full read · show the working · for Rainbow Trout · confidence 90%
How the 4 is built — score × weight = contribution
Temperature2 × 28%0.6
Flow80 × 22%17.6
Clarity85 × 18%15.3
Feeding Time55 × 13%7.2
Pressure75 × 7%5.3
Insect activity39 × 12%4.7
Limiting factor: Water temperature (23.1°C) is outside Rainbow Trout's preferred range (10–18°C)= 51
Can you trust it?
Water temperaturelive gauge readinggauge
Level / flowon-river gaugeobserved
Prey activitymodelled from regional profilemodelled
What would change the calculation
Cooler water — back toward the 10–18 °C ideal band — would lift the score and ease welfare.
The dawn and dusk windows score higher than the midday lull.
Directions
Seasons & zones
  • TroutSaturday of Memorial Day weekendFirst Sunday in November
Related guides
Booking & contacts