Yellowstone (inside YNP) Fishing Forecast
Fly fishers plan Montana trips on the Yellowstone (inside YNP) because it stacks credible wading access, recognizable insect cycles, and trout that respond when flows align. Expect classic freestone rhythm: push during stable or dropping flows after fronts, then back off when the river spikes and color returns in 24–48 hours. River-specific intel: The Yellowstone River inside Yellowstone National Park is the birthplace of western fly fishing. Native Yellowstone cutthroat trout swim in these historic waters. USGS gauge 06191500 tracks live flow and temperature for planning wade or float days.
Below the dam, the Yellowstone (inside YNP) is running at 1560 CFS through 61°F water — 5/10 today. Top pick: a Humpy.
Open Sat of Mem Day wknd* — First Sun in Nov
YNP fishing permit required (not state license). YNP Yellowstone River opens July 1. Other park waters open Sat Mem Day wknd. Park-specific regs
Forecast and on-page guide updated September 9, 2026 (UTC). Open the app for hourly conditions.
Today's Fishing Conditions
Fair
Updated 6:48 AM
61°F
1560 CFS
5 AM - 7 AM
Humpy
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What Makes the Yellowstone (inside YNP) Unique?
Signature hatch or window
BWO (Mayfly) is a headline hatch to watch in September. Peak activity often tracks 38–55°F water temps.
Distinctive access
Fishing Bridge: Historic area near Yellowstone Lake outlet.
Rules anglers miss
Park fishing permit required. Special regulations.
Optimal Fishing Conditions
Optimal Flow
3000 - 8000 CFS
Best fishing conditions
Optimal Water Temperature
50° - 62°F
Ideal for active trout
Quick Facts
Rainbow Trout, Brown Trout, and Cutthroat Trout
freestone
54°F - 64°F
September Hatches
BWO
Mayfly
Blue Wing Olives hatch on overcast days, spring and fall
Caddis
Caddis
Evening caddis hatches prolific through summer
Hopper
Terrestrial
Grasshoppers effective on windy afternoons
Trico
Mayfly
Early morning spinner falls, tiny flies
October Caddis
Caddis
Large fall caddis, evening emergence
September Fishing Tactics
Primary Targets
Recommended Tactics
Fall fishing improves. BWOs return, browns become aggressive.
Year-Round Fishing Guide
| Month | Water Temp | Tactics |
|---|---|---|
| January | 32-38°F | Nymphing, Midges, Small Streamers |
| February | 32-40°F | Nymphing, Midges, Small Streamers |
| March | 36-46°F | Dry Flies, BWOs, Skwala |
| April | 42-52°F | Dry Flies, BWOs, Skwala |
| May | 48-58°F | Dry Flies, BWOs, Skwala |
| June | 54-64°F | Hoppers, Terrestrials, PMDs |
| July | 58-68°F | Hoppers, Terrestrials, PMDs |
| August | 60-70°F | Hoppers, Terrestrials, PMDs |
| September(Now) | 54-64°F | Streamers, BWOs, October Caddis |
| October | 46-56°F | Streamers, BWOs, October Caddis |
| November | 38-46°F | Streamers, BWOs, October Caddis |
| December | 32-40°F | Nymphing, Midges, Small Streamers |
Recommended Equipment for Yellowstone (inside YNP)
Rod
9-foot, 5-weight is traditional.
Line
Floating line for dry fly fishing.
Leader & Tippet
9-foot tapered leader, 4X-5X tippet.
Waders
Breathable waders. Watch for wildlife while fishing.
Essential Flies
How to Fish Yellowstone (inside YNP): Tips & Tactics
The Yellowstone River inside Yellowstone National Park is the birthplace of western fly fishing. Native Yellowstone cutthroat trout swim in these historic waters.
Best Times of Day
The park opens July 15th for fishing. Summer offers excellent dry fly fishing. Fall brings larger fish and fewer crowds.
Recommended Techniques
Match the prolific hatches - PMDs, caddis, and Flavs. Dry fly fishing is the tradition. Native cutthroat are willing but require presentation.
Water Conditions
July 15th opening protects spawning cutthroat. Summer offers ideal conditions. Wildlife viewing is incredible.
Fly Selection
PMD and Flav patterns essential. Caddis throughout summer. Hopper patterns late summer. Traditional patterns work well.
When is the Best Time to Fish Yellowstone (inside YNP)?
Spring
Closed until July 15th to protect spawning.
Summer
Prime season after July 15th opening. Excellent hatches.
Fall
Larger fish, fewer crowds. Park closures may limit access.
Winter
Most sections closed. Limited access.
Access Points & Parking for Yellowstone (inside YNP)
Fishing Bridge
Historic area near Yellowstone Lake outlet.
Buffalo Ford
Famous section with quality fishing.
Canyon
Above the Grand Canyon of the Yellowstone.
Tower
Northern park access.
Spawning Seasons
Please respect spawning fish and their redds. Avoid fishing over actively spawning trout.
Brown Trout
Spawn months: October, November
Night spawning common. Males become very dark with pronounced kype during spawn.
Rainbow Trout
Spawn months: March, April
Resident rainbow trout spawn in smaller tributaries and tend to build smaller redds than steelhead.
Cutthroat Trout
Spawn months: May, June, July
Spring spawners. Timing varies by subspecies and elevation - coastal populations spawn earlier (Feb-Mar), inland populations later (May-July). Eggs develop for 6-7 weeks before hatching.
Yellowstone (inside YNP) Fishing Regulations
Season
Opens July 15th. Check park regulations.
Limits
Native cutthroat must be released.
Special Regulations
Park fishing permit required. Special regulations.
Bait Restrictions
Artificial flies and lures only.
Notes
Yellowstone National Park has unique regulations - read them.
Always verify current regulations with Montana fish and wildlife agency before fishing. Regulations can change annually.
Fly Shops & Guides Near Yellowstone (inside YNP)
Local Fly Shops
- Parks Fly Shop - Gardner
- Yellowstone Angler - Livingston
- Blue Ribbon Flies
Guide Services
- Parks Fly Shop Guides
- Yellowstone Guides
- Montana Trout Guides
Other Rivers You Might Like
Popular forecasts outside Montana—great for trip planning and comparing conditions.
Other Montana Trout Rivers
Bitterroot
Blackfoot
Madison
Missouri (below Holter)
Big Hole River
Yellowstone (inside YNP) — frequently asked questions
When is the best time to fish the Yellowstone (inside YNP)?
Fall fishing improves. BWOs return, browns become aggressive.
What flies should I bring to the Yellowstone (inside YNP)?
For the Yellowstone (inside YNP) (freestone), carry: PMD, Flav, Elk Hair Caddis, Hopper, Pheasant Tail.
What water temperature is best for trout on the Yellowstone (inside YNP)?
On the Yellowstone (inside YNP), trout hold between 50° and 62°F. In summer, expect temps to swing with air temperature — fish early.
Do I need a fishing license for the Yellowstone (inside YNP)?
Yes — you need a valid Montana fishing license to fish the Yellowstone (inside YNP). Local season: Opens July 15th. Check park regulations.. Daily limit: Native cutthroat must be released..
What hatches should I watch for on the Yellowstone (inside YNP) in September?
BWO is the signature hatch on the Yellowstone (inside YNP) in September. Match size and adjust leader size to 5X-6X. The fish key in on the emergence during low-light hours, so plan to be on the water at first light.
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