South Fork Snake River
Palisades Dam to Heise
SE Idaho, USA
Open live forecast →Target species: Brown, Rainbow, and Cutthroat.
Stream gauge: 13037500. Flow and water temperature update on every refresh.
Weekly AI Outlook as of 06/05/26
The South Fork is running 13,200 cfs with excellent clarity — perfect June flow for prime salmonfly action. The early June timing and stable conditions mean we're right in the heart of the legendary hatch window that makes this one of the West's best float trips. PMDs are also active midday, giving you surface options when the big stones aren't moving. With flows holding steady and no significant weather changes ahead, conditions are dialed for aggressive cutthroats feeding recklessly on the surface.
- Flow: 13,200 cfs with excellent clarity — ideal June level for accessing prime salmonfly water without safety concerns
- Hatches: Peak salmonfly window active with PMDs emerging midday. Golden stones following close behind the big bugs
- Water Temp: Cold tailwater temps 52-60°F keeping fish active all day, perfect for sustained surface feeding
- Best Window: All-day productivity with salmonflies moving morning/evening, PMDs midday 11am-2pm when air temps peak
Generated weekly from live USGS gauge readings, weather forecasts, and recent fly shop reports. Updates Friday mornings.
About this Water
- Tailwater
- Best months: June–Oct, peak Aug–Sept (hoppers & caddis)
The South Fork of the Snake is a blue-ribbon float fishery flowing through spectacular canyon country below Palisades Dam. Enormous dry fly fishing for cutthroat and rainbows — especially during the October Caddis and summer hopper season. The canyon section is roadless, accessed only by drift boat, making it one of the most remote and pristine blue-ribbon fisheries in Idaho.
The South Fork is world-famous for its bank-eating cutthroats during the summer hopper season — fish charge banks without hesitation.
January Outlook
The South Fork Snake is closed to fishing January 1 through April 30 in most sections to protect spawning cutthroat trout. This rest period is critical for the world-class fishery. A great month to plan your June Salmonfly float.
Productive Patterns
- Closed — winter/spring protection
Tips
The South Fork has a critical winter closure that protects its extraordinary cutthroat population. Plan the June float trip during the winter. Book guides well in advance — they fill quickly.
Water Notes
Palisades Dam regulated. Closed January–April 30. Cold winter flows.
February Outlook
Still closed under winter/spring protection regulations. The South Fork Snake receives no fishing pressure during this critical season.
Productive Patterns
- Closed — winter/spring protection
Tips
The closure protects spawning and rearing cutthroat trout. Open season begins May 1 but the Salmonfly hatch in June is the peak event — plan your trip accordingly.
Water Notes
Closed January 1–April 30. Palisades Dam regulated flows.
March Outlook
Closed through April 30. The South Fork is coming back to life under winter flows but protected from fishing. Pre-season preparations are underway at guide services in Swan Valley and Ririe.
Productive Patterns
- Closed — winter/spring protection
Tips
March is the planning month. Call Heise or Swan Valley outfitters to book your June or July float. The Salmonfly hatch dates are closely watched — typically late May to mid-June.
Water Notes
Closed. River awakening from winter under dam regulation.
April Outlook
Closed through April 30. The last month of the winter protection period. Flows begin building with snowmelt as the May opening approaches. The most anticipated open day in Idaho fly fishing is May 1.
Productive Patterns
- Closed — opens May 1
Tips
April 30 fishing reports from the Swan Valley area are eagerly anticipated. The first floats of the season begin May 1. Some anglers drive in for first light on opening day.
Water Notes
Closed through April 30. Flows building with spring snowmelt.
May Outlook
The South Fork of the Snake emerges from runoff as one of the finest cutthroat rivers in the West. PMD and Caddis hatches begin as flows drop.
Productive Patterns
- PMD Sparkle Dun
- Elk Hair Caddis
- Stimulator
- Hare's Ear
Tips
The South Fork requires a drift boat to fish effectively — the canyon walls make bank access limited. Book a guide for a first visit. The first float below Palisades Dam is the most productive.
Water Notes
Flows regulated by Palisades Dam. Target 4,000–8,000 cfs in May. Clear cold water 48–56°F.
June Outlook
Prime time on the South Fork. Salmonfly hatch moves through in early June followed by Golden Stones and PMDs. This is one of the best June float trips in the entire West.
Productive Patterns
- Salmonfly #4
- Golden Stone
- PMD
- Stimulator
Tips
The Salmonfly hatch on the South Fork is spectacular — large cutthroats feed recklessly on the surface. Chase the leading edge of the hatch upstream. Book well in advance.
Water Notes
6,000–12,000 cfs in early June dropping to 4,000–8,000 by late June. Cold 52–60°F. Float required.
July Outlook
Classic July floating with hopper-dropper and consistent caddis evening hatches. The cutthroats are aggressive and the scenery is spectacular.
Productive Patterns
- Hopper-Dropper
- Elk Hair Caddis
- PMD Cripple
- Stimulator
Tips
Float from Palisades Dam to Lorenzo or the lower sections. Hopper-dropper is the workhorse. Large cutthroats attack hoppers confidently.
Water Notes
3,000–6,000 cfs. Water 58–65°F. Beautiful canyon scenery. Excellent float conditions.
August Outlook
Hopper season in full swing. The South Fork's large cutthroats are known for aggressive surface takes. One of the best hopper rivers in the West.
Productive Patterns
- Dave's Hopper
- Chubby Chernobyl
- Parachute Ant
- Elk Hair Caddis
Tips
Fish the grassy bank edges and undercut willows. South Fork cutthroats eat hoppers confidently and give memorable fights. Float the full canyon for the best coverage.
Water Notes
2,500–4,500 cfs. Water 60–66°F. Excellent float conditions. Early morning is best on hot days.
September Outlook
Excellent fall fishing with BWO hatches and continued hopper action. The cutthroats are in peak condition before fall spawning.
Productive Patterns
- Blue Winged Olive
- Hopper
- Mahogany Dun
- Streamer
Tips
September is underrated on the South Fork. Less pressure than June–August with excellent fishing. The evening BWO hatch can produce spectacular dry fly action.
Water Notes
2,000–4,000 cfs. Cooling 54–62°F. Excellent clarity. Prime late-season float conditions.
October Outlook
Fall BWO season continues and brown trout from downstream join the cutthroats. Streamer fishing becomes productive.
Productive Patterns
- Streamer
- Blue Winged Olive
- Copper John
- Egg
Tips
October on the South Fork is exceptional with very little pressure. The fall BWO hatch produces rising fish throughout the float. Worth the trip.
Water Notes
1,800–3,500 cfs. Cold 48–56°F. Clear and beautiful.
November Outlook
November is the final month on the South Fork before the December 31 close. Excellent streamer fishing for large brown trout and the last BWO hatches of fall. A cold but rewarding month.
Productive Patterns
- Articulated Streamer
- Blue Winged Olive
- Egg
- Copper John
Tips
November on the South Fork is excellent for large fish with minimal pressure. Float from Palisades to Lorenzo for the most productive water. The season closes December 31 — fish the closing weeks actively.
Water Notes
1,500–3,000 cfs. Cold 40–50°F. Season closes December 31.
December Outlook
The South Fork Snake closes December 31. The final days of December provide the last fishing opportunity before the winter/spring closure that protects this extraordinary fishery through April 30.
Productive Patterns
- Streamer
- Midge Nymph
- Egg Pattern
Tips
Fish the final December days actively before the closure. The South Fork's large cutthroats and browns don't diminish in December. Cold but fishable through month end.
Water Notes
1,200–2,500 cfs. Very cold 36–44°F. Season closes December 31.
Hatch Calendar
| Insect | Peak | Active | Size | Productive Patterns |
|---|---|---|---|---|
| Pale Morning Dun Ephemerella infrequens |
Jul | Jun, Jul, Aug | #16–18 |
|
| Caddis Hydropsyche spp. |
Jun, Jul | May, Jun, Jul, Aug, Sep | #14–18 |
|
| Blue Winged Olive Baetis spp. |
May, Oct | Apr, May, Sep, Oct, Nov | #18–22 |
|
Access & Approach
Float trips launch at Palisades, Byington, or Lorenzo. No wade access in the canyon. Multiple-day float camping is a popular option.
Nearby Fly Shops
- TLAPC (The Lodge at Palisades Creek)
- WorldCast Anglers
- Westbank Anglers
- Snake River Angler
- JD High Country Outfitters
- Snake River Fly
Regulations & License
Fishing in Idaho requires a current license. Always verify season dates, bag limits, and any special-regulation waters before you fish.
Idaho fishing regulations & license →
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About Current
South Fork Snake River conditions on Current combine real-time flow data (USGS, WSC, CDEC, CEHQ), weather, tide predictions, hatch probabilities calibrated to this specific water, and recent fly shop reports from the area.
South Fork Snake River is one of 245 hand-curated waters in Current. The app and web forecast also generate AI outlooks for any unlisted river, lake, or saltwater flat anywhere in the world — drop a pin or paste a name and Current produces a fresh seasonal outlook with weather, flow context, and recommended techniques.
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