Bighorn River Winter Fishing Report: Midges, Nymphs, and Patience for Chunky Trout

Name’s Artificial Lure, checking in with your Big Horn country fishing report for the Bighorn River around Fort Smith and down toward Hardin. We don’t worry about tides out here—Bighorn’s a tailwater, not salt—but we do live and die by flows and weather. According to the Bureau of Reclamation gauges below Yellowtail, flows are running on the low, steady winter side, keeping that classic Bighorn green-olive tint and good clarity. With stable water and short days, the fish are settled into winter slots and feeding in predictable windows. Weather-wise, the National Weather Service is calling for a cold, mostly clear day in the valley: morning temps in the teens warming into the upper 20s to low 30s, light wind compared to our usual Big Horn breeze, and only a slight chance of flurries later. That means decent comfort if you layer right and great conditions for midge hatches. Sunrise is right around 7:40 a.m., sunset close to 4:25 p.m., so your real prime window is late morning through mid‑afternoon when that water bumps a degree or two. Montana Outdoor’s early‑December trout report has been saying southwest Montana tailwaters are fishing surprisingly well for winter, and the Bighorn is no exception. Local shop talk in Fort Smith is that the river has kicked out good numbers of chunky browns and rainbows in the 14–18 inch class this past week, with the occasional 20‑plus inch bow coming from deeper winter holes. Anglers running nymph rigs have been seeing steady action—nothing fast and furious, but a nice, consistent pick all day if you stay on the good water. Fish activity is classic winter: slower in the first couple hours of light, then a nice ramp‑up once the sun hits the canyon walls. You’ll see midges getting going late morning, and on the softer inside seams there have been pods of fish rising in that one‑to‑three‑o’clock window when the air calms down. Best producers right now: - Nymphs: small is king. Zebra midges, black or red, in sizes 18–22; Ray Charles and soft hackle sowbugs in tan or gray; tiny olive or brown mayfly patterns like Tailwater Tiny or Juju Baetis in 18–20. Run a double‑nymph rig under an indicator with enough split shot to tick bottom, 5X to the top fly, 6X to the dropper. - Dry flies: when noses show, go with a size 20–22 griffith’s gnat, CDC midge cluster, or a simple black parachute midge on long, fine tippet. You won’t get numbers on top, but you’ll get some of your better fish. - Streamers: for those who like to move and cover bank lines, small articulated patterns in olive, tan, or black have taken some heavy browns in the low light. Think Thin Mints, small Sparkle Minnows, or a scaled‑down Sex Dungeon. Fish them slow—short strips and long pauses. If you’re bait fishing on the reservoirs or slower side channels where it’s legal, think winter mode: nightcrawlers and leeches fished dead‑slow on the bottom. Perch and the odd walleye out of nearby stillwaters will still chew on a small jig tipped with a minnow. This content was created in partnership and with the help of Artificial Intelligence AI.