Big Hole River Fishing Forecast
The Big Hole River anchors Montana trout culture for anglers who want a forecast that respects real hydrology—not a generic “fish today” badge. Species mix centers on brown trout, rainbow trout, brook trout, and arctic grayling, with tactics shifting from weighted nymphs in cold water to dries and terrestrials as afternoons warm during late June through September. Because it is not a manicured park stretch, the Big Hole River rewards map work, respectful access, and leaders sized for the clarity you will actually see. USGS gauge 06025500 tracks live flow and temperature for planning wade or float days.
Below the dam, the Big Hole River is running at 219 CFS through 59°F water — 6/10 today. Top pick: a Adams.
Open 3rd Sat in May — Nov 30
Western District general season. Some sections have extended or special regs
Forecast and on-page guide updated September 8, 2026 (UTC). Open the app for hourly conditions.
Today's Fishing Conditions
Good
Updated 8:52 AM
59°F
219 CFS
5 AM - 7 AM
Adams
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What Makes the Big Hole River Unique?
Signature hatch or window
BWO (Mayfly) is a headline hatch to watch in September. Peak activity often tracks 45–55°F water temps.
Distinctive access
Wisdom: Upper river access in the Big Hole Valley.
Rules anglers miss
Hoot-owl restrictions may apply. Check FWP.
Optimal Fishing Conditions
Optimal Flow
500 - 1500 CFS
Best fishing conditions
Optimal Water Temperature
50° - 65°F
Ideal for active trout
Quick Facts
Brown Trout, Rainbow Trout, Brook Trout, and Arctic Grayling
freestone
48°F - 58°F
September Hatches
BWO
Mayfly
Best on overcast days. RS2, Parachute Adams. Spring and fall.
Trico
Mayfly
Early morning spinnerfall. Technical fishing. Size 20-22 spinners.
Hopper
Terrestrial
Bank-slapping hopper fishing. Dave's Hoppers, Moorish Hoppers.
September Fishing Tactics
Primary Targets
Recommended Tactics
Excellent fall fishing. Browns aggressive.
Year-Round Fishing Guide
| Month | Water Temp | Tactics |
|---|---|---|
| January | 32-38°F | Deep nymphing, Midges, Streamers |
| February | 33-40°F | Midges, Small nymphs, Deep pools |
| March | 36-45°F | BWO dries, Streamers, Early stonefly nymphs |
| April | 40-50°F | Skwala dries, BWO patterns, Streamers |
| May | 45-55°F | Mother's Day Caddis, Nymphing, Streamers |
| June | 50-60°F | Salmonfly dries, Golden Stones, PMDs |
| July | 55-68°F | PMDs, Hoppers, Caddis, Attractor dries |
| August | 55-70°F | Hoppers, Tricos, PMDs, Terrestrials |
| September(Now) | 48-58°F | BWOs, Streamers, Hoppers |
| October | 40-50°F | Streamers, BWOs, Egg patterns |
| November | 35-42°F | Streamers, Deep nymphs, Egg patterns |
| December | 32-38°F | Deep nymphs, Midges, Slow presentations |
Recommended Equipment for Big Hole River
Rod
9-foot, 5 or 6-weight for most fishing.
Line
Floating line for dries and nymphing.
Leader & Tippet
9-foot tapered leader, 4X-5X tippet.
Waders
Breathable waders. The Big Hole is wadeable in many sections.
Essential Flies
How to Fish Big Hole River: Tips & Tactics
The Big Hole River is Montana's last stronghold of fluvial Arctic grayling, alongside excellent populations of brown and rainbow trout. This is classic Montana ranching country.
Best Times of Day
The salmonfly hatch in late June is legendary. Summer offers excellent dry fly fishing. Fall brings aggressive brown trout feeding.
Recommended Techniques
Float fishing covers the most water. Match the prolific hatches - salmonflies, caddis, and mayflies. Target Arctic grayling in the upper river.
Water Conditions
The Big Hole can experience low summer flows. Hoot-owl restrictions may apply. The valley is stunning ranching country.
Fly Selection
Salmonfly and golden stonefly patterns for early summer. Caddis and mayflies throughout. Hoppers in late summer.
When is the Best Time to Fish Big Hole River?
Spring
Skwala and March browns begin the season.
Summer
Salmonfly hatch in late June. Watch for hoot-owl closures.
Fall
Brown trout become aggressive. Excellent conditions.
Winter
Limited but fishable on mild days.
Access Points & Parking for Big Hole River
Wisdom
Upper river access in the Big Hole Valley.
Divide
Mid-river access.
Melrose
Lower river access with services.
Glen
Lower canyon 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.
Brook Trout
Spawn months: September, October
Males develop vibrant red bellies and white-edged fins during spawning. Early fall spawners.
Big Hole River Fishing Regulations
Season
Open year-round.
Limits
Arctic grayling must be released. Trout limits vary.
Special Regulations
Hoot-owl restrictions may apply. Check FWP.
Bait Restrictions
Artificial flies and lures only.
Notes
Protecting Arctic grayling is critical.
Always verify current regulations with Montana fish and wildlife agency before fishing. Regulations can change annually.
Fly Shops & Guides Near Big Hole River
Local Fly Shops
- Frontier Anglers - Dillon
- Big Hole Lodge
- Complete Fly Fisher
Guide Services
- Frontier Anglers
- Big Hole Guides
- Complete Fly Fisher 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)
Big Hole River — frequently asked questions
When is the best time to fish the Big Hole River?
Excellent fall fishing. Browns aggressive.
What flies should I bring to the Big Hole River?
For the Big Hole River (freestone), carry: Salmonfly, Golden Stone, Elk Hair Caddis, Hopper, Skwala.
What water temperature is best for trout on the Big Hole River?
On the Big Hole River, trout hold between 50° and 65°F. In summer, expect temps to swing with air temperature — fish early.
Do I need a fishing license for the Big Hole River?
Yes — you need a valid Montana fishing license to fish the Big Hole River. Local season: Open year-round.. Daily limit: Arctic grayling must be released. Trout limits vary..
What hatches should I watch for on the Big Hole River in September?
BWO is the signature hatch on the Big Hole 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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