Southwestern Montana
SOUTHWESTERN MONTANA
ReportOCT 28 — NOV 4, 2026
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Flow
641CFS
Madison River bl Hebgen Lake nr Grayling MT
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Water Temp
50.4°F
Updated 2026-10-27
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Weather
21–39°F
Chance Snow Showers then Patchy Fog
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Reported By
Bruce Staples
On the water
The Madison below Hebgen Lake is running at 641 CFS with a water temperature of 50.4°F, putting mature brown trout deep into their spawning migration. Cold overnight lows in the low 20s and a chance of snow may affect road conditions, but midday windows on Wednesday and Thursday offer the best shot at dry-fly action.
From the ShopBruce Staples · October 28, 2026
Everywhere, mature brown trout are migrating to spawning areas. Streamers, woolly buggers, and large soft hackles are most effective for encountering these trout.
Midge activity is the major topwater choice, with BWOs active during middays. Weather has reduced bankside terrestrial insect populations and may impact driving conditions.
Caddis life cycle patterns attract trout during afternoons having nice weather.
What's Working — Hot Flies
Hatch Chart
| Insect | Size | Activity | Prime Time |
|---|---|---|---|
| Midges | #20–24 | High — primary topwater opportunity | Morning through afternoon |
| Blue-Winged Olive (BWO) | #22 | Moderate — look for rising fish | Midday |
| Caddis | #18–20 | Light — weather dependent | Afternoon on nicer days |
| Spawning Brown Trout (streamer/soft hackle trigger) | #4–12 | High — migration in full swing | All day |
Best Time Window
- MIDDAY (11am–2pm): Prime window for BWO and midge dry-fly action as temperatures peak — watch for rising fish in flats and tailouts
- AFTERNOON (2pm–dusk): Fish caddis life cycle patterns on days with decent sun; continue swinging streamers and soft hackles for migrating browns
- ALL DAY: Streamer and large soft hackle fishing for spawning brown trout is productive throughout daylight hours regardless of weather
Guide's Tip
From the benchThe staffer specifically calls out woolly buggers as a top producer for spawning browns — if you have them in your box, bring olive and black in sizes #6–10. Check road and access conditions before heading out, as overnight snow and temperatures in the low 20s could make approaches slick. Time your dry-fly window for midday when BWOs and midges are most active, then switch to caddis patterns if the afternoon sun holds.
Main Species
Brown Trout
Rainbow Trout
Mountain Whitefish
