Jefferson River Fishing Forecast
The Jefferson River is a Montana freestone where flows and clarity swing with storms—meaning the bite window can flip in a single afternoon. Anglers target brown trout and rainbow trout across riffles, seams, and undercut banks in this region, with prime dry-fly and nymph windows typically clustering in late June through September. USGS gauge 06036650 tracks live flow and temperature for planning wade or float days. Local tactics angle: The Jefferson River forms at Twin Bridges where the Big Hole and Beaverhead join. It flows to Three Forks where it becomes part of the Missouri River headwaters. TroutFishing pairs hatch timing with solunar windows so you know when to be on the water—not just where.
Spring-fed Jefferson River is flowing at 389 CFS CFS with surface temps near 66°F°F — 5/10 today. Top pick: a Parachute Hopper.
Open 3rd Sat in May — Nov 30
Western District general season
Forecast and on-page guide updated September 7, 2026 (UTC). Open the app for hourly conditions.
Today's Fishing Conditions
Fair
Updated 3:29 PM
66°F
389 CFS
3 AM - 5 AM
Parachute Hopper
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September Hatches
BWO
Mayfly
Extended season. Fall fishing can be outstanding.
Trico
Mayfly
Early morning spinner falls. Technical presentation required.
Caddis
Caddis
Evening caddis activity strong through summer.
Hopper
Terrestrial
Terrestrial season productive. Hopper-dropper rigs.
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 |
Quick Facts
Brown Trout and Rainbow Trout
freestone
48°F - 58°F
What Makes the Jefferson 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
Twin Bridges: Where the Big Hole and Beaverhead meet.
Rules anglers miss
Hoot-owl restrictions may apply in summer.
When is the Best Time to Fish Jefferson River?
Spring
Stoneflies and caddis emerge. Good early season fishing.
Summer
Can run warm - fish early. Watch for hoot-owl closures.
Fall
Browns become aggressive. Excellent conditions.
Winter
Limited but fishable on mild days.
Recommended Equipment for Jefferson River
Rod
9-foot, 5 or 6-weight for most fishing.
Line
Floating line for dries. Sink-tip for streamers.
Leader & Tippet
9-foot tapered leader, 4X-5X tippet.
Waders
Breathable waders. Wade carefully.
Essential Flies
How to Fish Jefferson River: Tips & Tactics
The Jefferson River forms at Twin Bridges where the Big Hole and Beaverhead join. It flows to Three Forks where it becomes part of the Missouri River headwaters.
Best Times of Day
Summer offers good fishing with diverse hatches. The river can run warm in late summer - fish early. Fall brings brown trout into spawning condition.
Recommended Techniques
Float fishing is the most effective method. Match the hatches when active. Streamers produce larger fish. Target structure and deeper water.
Water Conditions
The Jefferson can run warm and low in late summer. Hoot-owl restrictions may apply. Float fishing covers the most water.
Fly Selection
Caddis and stonefly patterns are essential. Hopper patterns in late summer. Streamers for brown trout. BWOs in fall.
Access Points & Parking for Jefferson River
Twin Bridges
Where the Big Hole and Beaverhead meet.
Waterloo
Mid-river access.
Cardwell
Lower river access.
Three Forks
Where Jefferson becomes the Missouri.
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.
Optimal Fishing Conditions
Optimal Flow
800 - 2000 CFS
Best fishing conditions
Optimal Water Temperature
50° - 65°F
Ideal for active trout
Jefferson River Fishing Regulations
Season
Open year-round.
Limits
Check Montana FWP for current regulations.
Special Regulations
Hoot-owl restrictions may apply in summer.
Bait Restrictions
Artificial flies and lures only.
Notes
Watch for low water conditions in summer.
Always verify current regulations with Montana fish and wildlife agency before fishing. Regulations can change annually.
Fly Shops & Guides Near Jefferson River
Local Fly Shops
- Four Rivers Fishing Company - Twin Bridges
- Frontier Anglers - Dillon
- Bozeman Anglers
Guide Services
- Four Rivers Guide Service
- Jefferson River Outfitters
- 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
Yellowstone (inside YNP)
Madison
Missouri (below Holter)
Jefferson River — frequently asked questions
When is the best time to fish the Jefferson River?
Excellent fall fishing. Browns aggressive.
What flies should I bring to the Jefferson River?
For the Jefferson River (freestone), carry: Elk Hair Caddis, Hopper, Woolly Bugger, Pat's Rubber Legs, BWO.
What water temperature is best for trout on the Jefferson River?
On the Jefferson 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 Jefferson River?
Yes — you need a valid Montana fishing license to fish the Jefferson River. Local season: Open year-round.. Daily limit: Check Montana FWP for current regulations..
What hatches should I watch for on the Jefferson River in September?
BWO is the signature hatch on the Jefferson 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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