Free Resource · Updated 2026

Au Sable River Fly Hatch Chart

Month-by-month hatch timing and fly pattern recommendations for the Au Sable River in 2026. Michigan's most celebrated wild trout fishery, home to the legendary Hex hatch and some of the best evening dry fly fishing in the country.

Wild Brown Trout · Brook Trout Freestone Grayling to Mio, MI Current Month Highlighted

About Au Sable River

The Au Sable River flows 138 miles from Grayling to Lake Huron through the jack pine plains of northern Michigan. The Holy Water stretch between Grayling and Wakeley Bridge is the most famous section — catch-and-release only, lightly developed, and home to self-sustaining wild brown trout that see heavy pressure during major hatches.

What sets the Au Sable apart is the density and variety of its hatches. The Hex hatch in late June draws fly fishers from across the country for massive nighttime emergences that push large fish to the surface. Brown Drakes in May and White Flies in August provide additional evening spectacles. The river fishes well with BWOs from early spring through fall on overcast days.

Access the Holy Water from the public launch at Stephan Bridge Road or at designated pullouts along Monument Road. The stretch above Wakeley Bridge runs through the Mason Tract, state-owned land with walk-in access only. Canoe traffic peaks mid-summer — fish early mornings or after dark during the Hex season for the best dry fly action.

See the full Michigan Fly Hatch Chart for hatch timing across all of Michigan's top trout streams.

Check Conditions Near Au Sable River

What to Fish

Au Sable River Key Hatches

Hex

Late June to Early July

Hexagenia limbata

The defining hatch of the Au Sable. Massive after-dark emergences in late June bring the largest fish in the river to the surface. The window is short — prime fishing runs from 10 PM to midnight. Bring a headlamp and fish big patterns in slow, smooth runs.

Recommended: Hex Paradrake, Hex Wiggle Nymph #4-6

Brown Drake

Late May to Early June

Ephemera simulans

An evening hatch that precedes the Hex by a few weeks. Brown Drakes emerge in slower water at dusk and draw large browns off the bottom. Fish the spinner fall the following evening when trout feed more selectively in the surface film.

Recommended: Brown Drake Paradrake #10-12

White Fly

August

Ephoron leukon

A late-summer evening spectacle. Huge numbers of white flies emerge after dark in August, triggering aggressive surface feeding. Fish are less selective than during the Hex, making this one of the more forgiving evening hatches on the river.

Recommended: White Wulff, White CDC Dun #14-16

Blue-Winged Olive

April and October

Baetis sp.

Two reliable windows: April through early May and again in October. Best on overcast, drizzly afternoons when BWOs hatch in steady numbers. These are the most technical presentations on the river — fine tippet and drag-free drifts in flat water.

Recommended: CDC Dun, Sparkle Dun #18-22