Southwestern Montana
SOUTHWESTERN MONTANA
ReportAUG 26 — SEP 2, 2026
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Flow
760CFS
Madison River bl Hebgen Lake nr Grayling MT
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Water Temp
61.3°F
Updated 2026-08-26
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Weather
46–79°F
Mostly Sunny then Chance Showers And Thunderstorms
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Reported By
Bruce Staples
On the water
The Madison at Hebgen Lake is running 760 CFS at 61.3°F, with afternoon thunderstorm chances both today and Thursday keeping anglers on their toes. Dropping flows on the Gallatin are concentrating fish in deeper runs, while Hebgen Lake's Madison Arm gulper fishing remains a highlight of the region.
From the ShopBruce Staples · August 26, 2026
From the no-boating section down to Ennis Lake, terrestrial insect patterns work best during daytime hours, with caddis life cycle patterns taking over as best during evenings. The river between Hebgen Lake and the Yellowstone Park boundary remains on a Hoot Owl restriction — check the Fish, Wildlife, and Parks website to find all Hoot Owl locations.
Gulpers on Hebgen Lake's Madison Arm provide some of the best fly fishing in southwest Montana. The Gallatin River flow is dropping, concentrating trout in deeper runs and pockets. They respond to patterns including those for spruce moths, yellow sallies, caddis, and traditional attractors.
What's Working — Hot Flies
Hatch Chart
| Insect | Size | Activity | Prime Time |
|---|---|---|---|
| Terrestrials (ants, hoppers) | #10–16 | Strong | Daytime |
| Caddis | #18–20 | Strong | Evening |
| Spruce Moths | #12–14 | Active | Midday–Afternoon |
| Yellow Sallies | #14–16 | Active | Afternoon |
| Gulpers (Hebgen Lake) | #18–22 | Excellent | Morning–Midday |
Best Time Window
- MORNING: Target Hebgen Lake's Madison Arm for gulping trout on small dries before afternoon winds develop
- MIDDAY–AFTERNOON: Fish terrestrial patterns on the Madison (no-boating section to Ennis Lake) and attractor/spruce moth patterns on the Gallatin's deeper runs and pockets
- EVENING: Switch to caddis life cycle patterns on the Madison for the best dry-fly action of the day
Guide's Tip
From the benchSpruce moths and yellow sallies are both producing on the Gallatin — carry imitations in #12–16 for the moths and #14–16 for the sallies, as the catalog doesn't carry a dedicated match for either right now. On Hebgen Lake, time your gulper session for the morning calm before afternoon winds pick up; the Madison Arm is the address. Be sure to check the FWP website for current Hoot Owl restriction boundaries before heading to the stretch between Hebgen Lake and the Yellowstone Park boundary.
Main Species
Brown Trout
Rainbow Trout
Mountain Whitefish
