Gallatin River
Gallatin Canyon · Big Sky to Bozeman
SW Montana, USA
Open live forecast →Target species: Brown and Rainbow.
Stream gauge: 06043500. Flow and water temperature update on every refresh.
Weekly AI Outlook as of 07/31/26
The Gallatin is running 538 cfs through the canyon — down slightly from Rivers Edge's 557 CFS reading on July 29, dropping into solid wade-fishing shape. Water is clear in the upper canyon; Swan Creek mud after recent rain has pushed color into the lower stretch, so concentrate your efforts mid-canyon and above. Caddis, PMDs, yellow sallies, and spruce moths are all in play, with fish willing to come to the surface mornings and during the last two hours of daylight. Nymphing carries midday when surface activity stalls. With highs touching 95-96°F Saturday-Sunday and wind ramping to 24 mph, get on the water early — heat stress will shut down surface feeding by afternoon. Dry-dropper rigs (caddis or yellow sally up top, split-case PMD or sparkle pupa below) are the most versatile setup right now. The forecasted drop to 73°F on Monday could reset conditions quickly, so watch for a renewed afternoon window late in the weekend.
- Flow: 538 cfs — wading the canyon is comfortable. Avoid the lower river near Swan Creek where storm runoff has added color. Upper canyon running clear.
- Hatches: Caddis, PMDs, yellow sallies, and spruce moths all active. Mornings and last 2 hrs of light are prime dry-fly windows. Nymphs best midday through the heat.
- Water Temp: Canyon temps expected in the low 60s°F — within the PMD/caddis sweet spot but watch for fish going off feed if afternoon air temps push water toward upper 60s.
- Best Window: Early morning until ~10am, then again 6-8pm. Sat-Sun highs of 95-96°F with 17-24 mph wind make midday fishing genuinely tough — plan accordingly.
Generated weekly from live USGS gauge readings, weather forecasts, and recent fly shop reports. Updates Friday mornings.
About this Water
- Freestone
- Best months: June–Oct, peak July–Sept
The Gallatin tumbles out of Yellowstone National Park through a stunning canyon before opening into the Gallatin Valley. It's a classic Montana freestone river — energetic riffles, pocketwater, and a surprising density of brown and rainbow trout for its size. The canyon stretch alongside US-191 provides easy access, making it ideal for visiting anglers.
Parts of the canyon featured in A River Runs Through It, giving the Gallatin iconic status among fly fishing films.
January Outlook
The Gallatin canyon in winter is a cold but surprisingly productive midge fishery. The canyon walls trap heat and the river stays open most winters. Deep pools below rapids hold concentrated fish.
Productive Patterns
- Zebra Midge
- RS2
- Juju Baetis
- WD-40
Tips
Fish the canyon between Big Sky and Gallatin Gateway — the most sheltered section. Target noon–2pm. Indicator nymph rigs with small midges. Dress warmly — the canyon stays cold even on mild days.
Water Notes
250–500 cfs. Water 34–40°F. Canyon sections stay open; valley sections may freeze partially.
February Outlook
February midging on the Gallatin. As days lengthen, the canyon slowly warms and BWO sightings on afternoons become possible. The river's freestone character means winter fishing is variable but always worthwhile.
Productive Patterns
- Zebra Midge
- Vis-A-Dun #20
- RS2
- Soft Hackle
Tips
Canyon section above Gallatin Gateway fishes best in February. Fish the slow inside seams where ice hasn't formed. A warm afternoon can produce a brief BWO window.
Water Notes
300–500 cfs. Stable if cold. Canyon runs colder than valley. Water 38–46°F.
March Outlook
One of Montana's first rivers for consistent BWO activity. Canyon sections below Big Sky produce on overcast afternoons.
Productive Patterns
- Sparkle Dun #18
- Zebra Midge
- RS2
- Soft Hackle
Tips
Work slower runs methodically — fish are in predictable lies after winter. Afternoon BWOs are the highlight.
Water Notes
300–600 cfs. Clear and manageable. Canyon character requires wading in the river.
April Outlook
Skwala stoneflies arrive. The Gallatin's freestone character means runoff comes earlier than other rivers — fish the first two weeks.
Productive Patterns
- Skwala Stone
- Beadhead Hare's Ear
- Brown Rubber Leg
- Sparkle Dun
Tips
Get on the water before runoff peaks. Canyon sections above Gallatin Gateway run cleaner than valley sections below.
Water Notes
Runoff starts mid-April. Flows rise from 600 to 2,500+ cfs. Check the gauge daily.
May Outlook
Gallatin clearing after runoff. Caddis and PMDs arrive. The canyon section fishes best as flows drop.
Productive Patterns
- Elk Hair Caddis
- PMD Sparkle Dun
- Stimulator
- Hare's Ear
Tips
Focus on the canyon stretch from Big Sky to highway pullouts as flows drop. Valley section clears last.
Water Notes
Flows dropping from peak — target below 1,200 cfs and improving clarity.
June Outlook
Best month on the Gallatin. Golden Stones, PMDs, and Caddis in the spectacular canyon with the river in prime shape.
Productive Patterns
- Golden Stone
- PMD
- Elk Hair Caddis
- Stimulator #10
Tips
Wade the canyon pools carefully — steep gradient and tricky footing. Evening caddis hatches from pullouts above Big Sky are classic.
Water Notes
600–1,200 cfs in late June. Crystal clear, cold 52–58°F.
July Outlook
Hopper fishing in the valley, continued dry fly in the canyon. Two different characters within one river.
Productive Patterns
- Hopper-Dropper
- PMD Cripple
- Stimulator
- Woolly Bugger
Tips
Fish the canyon in the morning before it gets hot. Move to valley sections for hopper fishing in the afternoon.
Water Notes
500–900 cfs. Water 60–66°F. Canyon stays cooler than the valley.
August Outlook
Hopper and terrestrial month throughout the valley. Fish the meadow for cut banks and the canyon for technical challenge.
Productive Patterns
- Dave's Hopper
- Chubby Chernobyl
- Parachute Ant
- Elk Hair Caddis
Tips
Meadow sections near trailheads are overlooked. Cut banks in the meadow hold large fish that eat hoppers confidently.
Water Notes
400–700 cfs. Valley sections warm — fish early. Canyon runs cooler mid-afternoon.
September Outlook
Excellent. BWO hatches return, pressure drops, and the Gallatin's cutthroat and brown trout are very active. Top-10 September river in Montana.
Productive Patterns
- Blue Winged Olive
- Hopper
- Elk Hair Caddis
- Mahogany Dun
Tips
BWO hatch window 1–4pm on overcast afternoons. Size 18–22 works best. Canyon provides ample sight fishing.
Water Notes
350–650 cfs. Clear and cold 50–58°F. Excellent wading.
October Outlook
Fall BWO season and brown trout streamer fishing. The Gallatin's smaller size makes it an intimate autumn fishery.
Productive Patterns
- Streamer
- Blue Winged Olive
- Copper John
- Egg
Tips
Work streamers through deeper pools and undercut banks. Browns moving up from lower river concentrate in the canyon pools.
Water Notes
300–500 cfs. Very clear. Brown trout spawning activity begins.
November Outlook
Quiet but midges produce fish on mild days. Good option when other rivers are off.
Productive Patterns
- Zebra Midge
- Juju Baetis
- Pheasant Tail #20
- RS2
Tips
Canyon holds warmth longer than the open valley sections. Target noon–2pm. Fish in deepest, slowest pools and side pockets.
Water Notes
300–450 cfs. Stable and clear. Canyon sections stay open longer.
December Outlook
December on the Gallatin is for the dedicated few. Midge hatches concentrate in the canyon's sheltered pools on mild days. The river's proximity to Bozeman makes it worth visiting when weather cooperates.
Productive Patterns
- Zebra Midge
- Mercury Midge
- RS2
- WD-40
Tips
Choose the warmest day in a stretch of decent weather. Canyon sections hold heat better than valley. Fish noon–2pm at most. Two small midges under a small indicator.
Water Notes
250–450 cfs. Variable winter flows. Canyon stays open more reliably than valley sections.
Hatch Calendar
| Insect | Peak | Active | Size | Productive Patterns |
|---|---|---|---|---|
| Skwala Stonefly Skwala americana |
Mar, Apr | Mar, Apr | #8–10 |
|
| Blue Winged Olive Baetis tricaudatus |
Apr, Oct | Mar, Apr, May, Sep, Oct, Nov | #18–22 |
|
| Salmonfly Pteronarcys californica |
Jun | Jun, Jul | #4–8 |
|
| Golden Stonefly Hesperoperla pacifica |
Jun, Jul | Jun, Jul | #8–12 |
|
| Yellow Sally Isoperla / Chloroperlidae |
Jul | Jun, Jul, Aug | #10–14 |
|
| Pale Morning Dun Ephemerella inermis |
Jul, Aug | Jul, Aug, Sep | #16–18 |
|
| Caddis Hydropsyche / Brachycentrus spp. |
Jul, Aug | Jun, Jul, Aug, Sep | #12–18 |
|
| Trico Tricorythodes spp. |
Aug | Aug, Sep | #20–24 |
|
| October Caddis Dicosmoecus gilvipes |
Oct | Sep, Oct | #8–10 |
|
| Hoppers Acrididae / Tettigoniidae |
Aug | Jul, Aug, Sep | #8–12 |
|
Access & Approach
Roadside pullouts along US-191 provide easy wade access through the canyon. The river is public from Yellowstone NP boundary to Manhattan. No fees required outside YNP.
Nearby Fly Shops
- Fins & Feathers of Bozeman
- Yellow Dog Flyfishing
- Rivers Edge
- Bozeman Fly Supply
- Montana Angler
- Yellowstone Angler
Regulations & License
Fishing in Montana requires a current license. Always verify season dates, bag limits, and any special-regulation waters before you fish.
Montana fishing regulations & license →
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About Current
Gallatin 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.
Gallatin 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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