Rules at a glance
- Fly only
Water temperature for Brown Trout
Warm — slow16°C est.ideal 10–16°C
0°14°28°
How to fish it · for Brown 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
Excellent — water temperature is working for you, but insect activity is the limiting factor today.
Likely species
Mayflies
Mayflies
Gammarids
Hatch timeline · todayQuiet day
Low insect activity predicted today
Sub-surface · on the nymphunder the surface
Hatch predictions
Supporters see the full sub-surface read.
Start free trial14-day free trial. Cancel anytime.
Beyond the hatch · worth watchingambient prey(1)
Hatch predictions
Supporters see what else is on the menu.
Start free trial14-day free trial. Cancel anytime.
Evidence
Records-basedModerate confidence
Based on species-occurrence records, not local invertebrate surveys.
Through the year
0–3 scale · October highlighted
J
F
M
A
M
J
J
A
S
O
N
D
Brown DunHatch
2
3
3
3
3
3
3
2
Western Green DrakeHatch
2
2
Flav (Small Western Green Drake)Hatch
2
3
2
Mahogany DunHatch
2
2
Numbers are intensity 0 (none) to 3 (peak) — a guide, not a guarantee.
Ranked for today
Fly box · Brown Trout
2-6 · Pattern
Proven pattern for this period
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
Other water nearby · 5
Gallery · 2
Visitors fishing the Firehole River Terrain map
The full read · show the working · for Brown Trout · confidence 75%
How the 83 is built — score × weight = contribution
Temperature100 × 28%28.0
Flow80 × 22%17.6
Clarity95 × 18%17.1
Feeding Time70 × 13%9.1
Pressure80 × 7%5.6
Insect activity44 × 12%5.3
Conditions total= 83
Can you trust it?
Water temperaturelive gauge readinggauge
Level / flowon-river gaugeobserved
Prey activitymodelled from regional profilemodelled
Directions
Seasons & zones
- Trout Saturday im Memorial Day weekend → Erster Sunday in November
Related guides
Booking & contacts
Firehole River
Water temperature for Brown Trout
Warm — slow16°C est.ideal 10–16°C
0°14°28°
How to fish it · for Brown 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
Excellent — water temperature is working for you, but insect activity is the limiting factor today.
Likely species
Mayflies
Hatch timeline · todayQuiet day
Low insect activity predicted today
Sub-surface · on the nymphunder the surface
Hatch predictions
Supporters see the full sub-surface read.
Start free trial14-day free trial. Cancel anytime.
Beyond the hatch · worth watchingambient prey(1)
Hatch predictions
Supporters see what else is on the menu.
Start free trial14-day free trial. Cancel anytime.
Evidence
Records-basedModerate confidence
Based on species-occurrence records, not local invertebrate surveys.
Through the year
0–3 scale · October highlighted
J
F
M
A
M
J
J
A
S
O
N
D
Brown DunHatch
2
3
3
3
3
3
3
2
Western Green DrakeHatch
2
2
Flav (Small Western Green Drake)Hatch
2
3
2
Mahogany DunHatch
2
2
Numbers are intensity 0 (none) to 3 (peak) — a guide, not a guarantee.
Ranked for today
Fly box · Brown Trout
2-6 · Pattern
Proven pattern for this period
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
Other water nearby · 5
Gallery · 2
Visitors fishing the Firehole River Terrain map
The full read · show the working · for Brown Trout · confidence 75%
How the 83 is built — score × weight = contribution
Temperature100 × 28%28.0
Flow80 × 22%17.6
Clarity95 × 18%17.1
Feeding Time70 × 13%9.1
Pressure80 × 7%5.6
Insect activity44 × 12%5.3
Conditions total= 83
Can you trust it?
Water temperaturelive gauge readinggauge
Level / flowon-river gaugeobserved
Prey activitymodelled from regional profilemodelled
Directions
Seasons & zones
- Trout Saturday im Memorial Day weekend → Erster Sunday in November
Related guides
Booking & contacts