Montana ·
Madison River Fly Fishing Report - August 16, 2026
MADISON RIVER
ReportAUG 16 — 23, 2026
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Flow
806CFS
Madison River bl Hebgen Lake nr Grayling MT
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Water Temp
59.7°F
Updated 2026-08-15
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Weather
42–74°F
Slight Chance Rain Showers
💧
Clarity
Clear
Check post-storm
Flow is running at 806 CFS below Hebgen Lake with a comfortable water temperature of 59.7°F — Northwestern Energy releases are keeping the river cool and fish active well into the afternoon. Expect patchy morning fog clearing to partly sunny skies with a slight chance of afternoon thunderstorms near midday.
What's Working — Hot Flies
Bionic Hopper - Tan #12
#12
Bionic Hopper - Purple #12
#12
Bionic Ant 2.0 - Black #16
#16
Bionic Ant 2.0 - Brown #12
#12
Corn-fed Caddis (CDC) Tan #20
#20
Corn-fed Caddis (CDC) Olive #20
#20
Tungsten Split Case Nymph - PMD #20
#20
Stealth Link Mercer - PMD #20
#20
Tungsten Pat's Rubber Legs - Tan & Brown #6
#6
Egan's Thread Frenchie Jig - Olive #12
#12
Black Zebra Midge(TBH) #20
#20
Coffey's CH Sparkle Minnow Sculpin #6
#6
Hatch Chart
| Insect | Size | Activity | Prime Time |
|---|---|---|---|
| Grasshoppers | 10-14 | Heavy | 11 AM - 5 PM |
| Ants / Terrestrials | 14-18 | Moderate | 10 AM - 3 PM |
| Caddis | 18-20 | Moderate | 6 PM - Dusk |
| PMD (Pale Morning Dun) | 18-20 | Light | 9 AM - 12 PM |
| Midge | 20-22 | Light | 7 AM - 9 AM |
| Stonefly (late season) | 6-8 | Light | 8 AM - 11 AM |
Best Time Window
- 6:30 AM - 9:00 AM: Early midge and PMD nymphing in the slower flats before fog burns off — fish are stacked and feeding subsurface.
- 10:00 AM - 12:00 PM: Prime hopper and ant time along grassy banks before afternoon storm threat builds — work the inside bends hard.
- 6:00 PM - Dusk: Evening caddis rise in the tailouts and slower pools — switch to CDC caddis patterns on fine tippet for sipping risers.
Guide's Tip
From the benchWith flows at 806 CFS and water temps a cool 59.7°F, fish are comfortable and feeding aggressively — don't waste the midday window. Work the hopper tight to the grassy banks on the inside bends where the current slows; cast at a 45-degree downstream angle and mend immediately to buy yourself a long, drag-free drift. If you see afternoon thunderstorms building around noon, get off the water early and switch to nymphs in the deeper runs before the storm hits — fish often feed hard in the 20 minutes before a storm rolls through. Keep your tippet at 4X for hoppers and drop to 5X or 6X for the smaller caddis and PMD patterns in the evening.
Main Species
Brown Trout
Rainbow Trout
Mountain Whitefish
