Bighorn River Report: Cool Mornings, Steady Hatches, and Big Trout in Western Montana

This is Artificial Lure with your September 13th, 2025 fishing report for Big Horn, Montana and nearby waters. First light crept over the Bighorn River at 6:43 AM this morning; expect sunset at 7:34 PM, giving anglers plenty of daylight for both early rises and easy twilight fishing. Weather-wise, we woke to cool air around 48°F, brisk but pleasant, trending up to the low 70s by late afternoon. Intermittent clouds drifted in from the northwest, making for ideal fish activity windows: not too hot, and just enough overcast for those big browns to leave their lairs. No need to check for tides here in the heart of Montana—this is classic western trout country, with the long Bighorn riffle-and-pool stretches beneath spacious autumn skies. Water levels are steady and clear, courtesy of well-managed outflows from Yellowtail Dam. As of this week, visibility has been excellent, sitting at around 4-5 feet which means fish can see your presentation but won’t get easily spooked. The bite has been consistent. Locals and guides report strong action on rainbows averaging 15-18", plenty in the slot, with good numbers of browns showing, some sneaking north of 20". Late summer hatches are tapering but still productive; Tricos and black caddis continue to trickle off mid-morning, while PMDs have lingered longer than usual—match the hatch! Reports from the Bighorn Trout Shop and a few reliable river rats drifting down from Afterbay confirmed a couple of chunky cutthroat came to net this week as well. For today, nymphing remains king. Top patterns: a size 16-18 Ray Charles in tan or gray, black Zebra Midges, and wire worm or San Juan Worm as lead. Dry fly diehards are finding subtle sippers in slick water—have your Trico spinners (size 20-22), and black or olive CDC caddis ready if clouds roll in. Anglers chucking streamers like olive or black Buggers and small articulated patterns found browns pushing out of deeper slots right before dusk, especially near gravel drop-offs. Bait fishing is rare in these stretches but if you slip into the reservoirs, a nightcrawler or leech under a slip float can tempt those less pressured walleye and the occasional hungry perch. Just mind area regulations—catch and release for a lot of the prime river run. Hot spots today: - Three Mile Access: Top pick for both wade and float anglers. It’s been loaded with feeding trout holding tight to the seams; drop anchor near the bottom of riffles, and don’t overlook the shallows after 3 PM. - Afterbay to 13 Mile: That five mile drift has been producing all week—target the tailouts early, then switch to bankside structure as the sun gets higher. For folks heading out, with archery season underway and more hunters in camo dotting the landscape, keep your blaze orange handy at shore and respect private boundaries. Take a detour to the Yellowtail Dam Visitor Center if the fishing slows—water levels and flow info are posted daily. Thanks for tuning in to your local river rundown. Subscribe f This content was created in partnership and with the help of Artificial Intelligence AI.