August is a genuine best-of-both-worlds month on the Bighorn — full Trico spinner falls at dawn and peak hopper season by afternoon. Here is exactly what our guides are seeing on the water right now.
Current Conditions — Late August 2026
Flows are running at 1,530 CFS — manageable, wadeable, and concentrating fish beautifully in classic seams and tailouts. Water clarity is exceptional. The tailwater below Yellowtail Dam maintains a consistent 52-58°F even as air temperatures have been climbing into the 90s — the reason the Bighorn keeps fishing hard all summer while every other river in Montana has shut down.
It has been a brutally hot August on the Bighorn — but as we head into the final stretch of the month temperatures are settling into the low to mid-90s, making for much more comfortable days on the water. After a fabulous hot breakfast guests are shortly on the river catching the prime morning fishing window. Guides bring guests in with plenty of time to relax before appetizers at 7 PM and dinner at 7:30 PM.
The Hatches
Trico spinner falls are the most reliable event of the day — arriving almost like clockwork within an hour of sunrise on calm mornings. Hoppers have taken over along the banks by early afternoon and stay productive through the evening. Caddis — both tan and black — are hatching in strong numbers in the evenings, bringing fish out of their daytime lies and into the riffles and seams. A few PMDs are still showing on overcast mornings.
What's Working Right Now
Nymphs
- Tailwater Sowbug #16 — always in the rig
- Trico Spinner #20-22 — dawn and early morning
- Tungsten Split Case PMD Nymph #20 — excellent mid morning
- Egan's Frenchie #12 — excellent in the seams
- Black Zebra Midge #20 — mornings
- Tungsten Rainbow Warrior #14 — working well right now
- Roza's World Spain Perdigon #18 — reliable all day
- Pheasant Tail dropper #18 — consistent throughout the day
Dries
- Dave's Hopper #8-10 — tight to the banks all afternoon
- Tan Chubby Chernobyl #8 — hopper season is fully on
- Two dry fly combo — hopper #8-10 with an ant or beetle #14-18 as a dropper
- Bionic Ant 2.0 Black #16 — excellent along the banks
- Corn-fed Caddis CDC Tan #20 — evening caddis hatch
- Elk Hair Caddis Black #16 — evenings along the banks
- Trico Spinner #20-22 — first light on calm mornings
- Foam Beetle #14 — along grassy edges
Streamers
- Coffey's Sparkle Minnow Sculpin #6 — first and last light
- Heavy sculpin pattern — slow bottom-hugging strip in shaded deeper pools midday
Guide Tip for Late August
By late August Bighorn browns have seen thousands of hoppers drift by. If a fish rises and turns away at the last second — give the fly one small twitch, just enough to make it kick like a hopper trying to swim off the surface, then let it sit again. That flash of panicked movement often triggers the fish that refused the perfect presentation to come back and eat.
A Note on Licenses
Montana Fish, Wildlife & Parks no longer allows fishing licenses to be sold at the lodge or any fly shop. Purchase your license online at ols.fwp.mt.gov before you leave home. Cell service can be unreliable in Fort Smith — take care of this before you arrive.
We have a small window of availability in early September. Call us at 800.665.3799 or email info@forrestersbighorn.com.
Forrester's Bighorn River Resort — Fort Smith, Montana
Orvis-endorsed fly fishing since 1992 | 800.665.3799 | forrestersbighorn.com