Bighorn River Fishing Forecast
Fly fishers plan Montana trips on the Bighorn River because it stacks credible wading access, recognizable insect cycles, and trout that respond when flows align. Below-dam hydrology keeps dissolved oxygen high through summer—ideal for brown trout and rainbow trout when roadside freestones climb past comfortable temperatures. River-specific intel: The Bighorn River is one of America's legendary tailwaters, producing trophy brown and rainbow trout in incredible numbers. Fish counts consistently exceed 5,000 trout per mile. USGS gauge 06287000 tracks live flow and temperature for planning wade or float days.
Today's Bighorn River is reading 62°F and 1550 CFS. That's a 7/10 day on the water. Top pick: a X-Caddis.
Open year-round (check section regs)
Central District - rivers open year-round unless specified. Blue-ribbon fishery
Forecast and on-page guide updated September 8, 2026 (UTC). Open the app for hourly conditions.
Today's Fishing Conditions
Good
Updated 11:00 AM
62°F
1550 CFS
4 AM - 6 AM
X-Caddis
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What Makes the Bighorn River Unique?
Signature hatch or window
BWO (Mayfly) is a headline hatch to watch in September. Peak activity often tracks 42–55°F water temps.
Distinctive access
Afterbay Dam: Immediately below dam - trophy water.
Rules anglers miss
First 3 miles have special regulations.
Optimal Fishing Conditions
Optimal Flow
2500 - 5000 CFS
Best fishing conditions
Optimal Water Temperature
45° - 55°F
Ideal for active trout
Quick Facts
Brown Trout and Rainbow Trout
tailwater
48°F - 56°F
September Hatches
BWO
Mayfly
Year-round tailwater BWO fishing. Spring and fall prime. Overcast days best.
Trico
Mayfly
Early morning spinner falls. Technical dry fly fishing.
Caddis
Caddis
Evening caddis activity. Sparkle Pupae effective.
Scud
Crustacean
Year-round subsurface staple. Pink, gray, olive scuds essential.
Sowbug
Crustacean
Year-round nymphing. Ray Charles, Miracle Nymph patterns.
San Juan Worms
Aquatic Worm
After rain events most effective. Red, pink, brown colors.
September Fishing Tactics
Primary Targets
Recommended Tactics
Fall BWOs return. Excellent dry fly.
Year-Round Fishing Guide
| Month | Water Temp | Tactics |
|---|---|---|
| January | 38-45°F | Midges, BWOs, Scuds, Sowbugs |
| February | 38-46°F | Midges, BWOs, Scuds |
| March | 40-48°F | BWOs, Midges, Early PMDs |
| April | 42-50°F | BWOs, Midges, PMD nymphs |
| May | 45-52°F | BWOs, PMDs, Caddis |
| June | 48-55°F | PMDs, Caddis, Tricos starting |
| July | 50-58°F | PMDs, Tricos, Caddis |
| August | 50-60°F | Tricos, PMDs, Hoppers |
| September(Now) | 48-56°F | BWOs, Tricos, Streamers |
| October | 45-52°F | BWOs, Midges, Streamers |
| November | 42-48°F | BWOs, Midges, Scuds |
| December | 38-45°F | Midges, BWOs, Scuds, Sowbugs |
Recommended Equipment for Bighorn River
Rod
9-foot, 5-weight is standard.
Line
Floating line for most fishing.
Leader & Tippet
9-12 foot leaders, 5X-6X tippet.
Waders
Breathable waders. Cold water year-round.
Essential Flies
How to Fish Bighorn River: Tips & Tactics
The Bighorn River is one of America's legendary tailwaters, producing trophy brown and rainbow trout in incredible numbers. Fish counts consistently exceed 5,000 trout per mile.
Best Times of Day
Year-round fishing is excellent due to stable dam releases. Midge and mayfly hatches occur daily. The river fishes well even in challenging conditions.
Recommended Techniques
Float fishing is the primary method. Match the prolific midge, sowbug, and mayfly hatches. Nymphing is highly effective. Dry fly fishing during hatches.
Water Conditions
Dam releases create perfect conditions year-round. Water clarity is excellent. The Bighorn is consistent and productive.
Fly Selection
Sowbugs and scuds are essential. Midge patterns in sizes 18-22. San Juan Worms year-round. PMDs and BWOs for mayflies.
When is the Best Time to Fish Bighorn River?
Spring
Excellent fishing with increasing hatches.
Summer
PMD and caddis hatches. Fish throughout the day.
Fall
Brown trout become aggressive. Trophy season.
Winter
Year-round tailwater stays productive. Midge focus.
Access Points & Parking for Bighorn River
Afterbay Dam
Immediately below dam - trophy water.
Three Mile
Most popular access point.
Thirteen Mile
Mid-river access.
Bighorn
Lower river access near town.
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.
Bighorn River Fishing Regulations
Season
Open year-round.
Limits
Check Montana FWP for current regulations.
Special Regulations
First 3 miles have special regulations.
Bait Restrictions
Artificial flies and lures only.
Notes
The Bighorn flows through Crow Reservation - respect tribal regulations.
Always verify current regulations with Montana fish and wildlife agency before fishing. Regulations can change annually.
Fly Shops & Guides Near Bighorn River
Local Fly Shops
- Bighorn Angler - Fort Smith
- Cottonwood Camp
- Bighorn Trout Shop
Guide Services
- Bighorn Angler Guides
- Cottonwood Camp Guides
- Bighorn River Guides
Other Rivers You Might Like
Popular forecasts outside Montana—great for trip planning and comparing conditions.
Other Montana Trout Rivers
Bitterroot
Blackfoot
Yellowstone (inside YNP)
Madison
Missouri (below Holter)
Bighorn River — frequently asked questions
When is the best time to fish the Bighorn River?
Fall BWOs return. Excellent dry fly.
What flies should I bring to the Bighorn River?
For the Bighorn River (tailwater), carry: Sowbug, Scud, San Juan Worm, PMD, Midge.
What water temperature is best for trout on the Bighorn River?
On the Bighorn River, trout hold between 45° and 55°F. Because the river is dam-fed, the temperature stays in this band year-round.
Do I need a fishing license for the Bighorn River?
Yes — you need a valid Montana fishing license to fish the Bighorn River. Local season: Open year-round.. Daily limit: Check Montana FWP for current regulations..
What hatches should I watch for on the Bighorn River in September?
BWO is the signature hatch on the Bighorn River 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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