Big Horn River Fishing Report: Dry Flies, Nymphs, and Chasing Biguns

Artificial Lure checking in with your Big Horn, Montana fishing report for Saturday, August 9th, 2025. Sunrise this morning brought calm, clear skies and cool temps in the 50s, but things are heating up fast—expect the mercury to push into the lower 90s by mid-afternoon, so pack those sun hats and plenty of water. Winds are light out of the northwest at 5–15 mph, keeping conditions pleasant most of the day. For you night owls, sunset’s lined up at 8:29 pm, with a warm, mostly clear night ahead. No tidal swings here in the interior, but river flows remain a key to today’s game. Turning to the water, the Bighorn River is right in its prime summer groove. According to Fins & Feathers Guide Service, mornings are kicking off with strong PMD (pale morning dun) hatches, drawing trout into the seams and soft water. Fish have settled into those classic summer runs, and anglers are reporting steady numbers on both nymph and dry fly setups. Top trout species this week are rainbows and browns, averaging 14–18 inches, though a few beefier browns up to 22” have hit the net downstream from Fort Smith. The bite has been best from first light until about 11 am, before surface action tapers off in the heat. Nymphing is the mainstay right now, and if you’re looking to land numbers, it’s hard to beat a two-fly rig. Guides are scoring with Mega Prince, Pat’s Rubberlegs, and FKA Prince in sizes 8–14, trailed by a beadhead PMD nymph or a small soft hackle. For dry fly purists, the late-morning PMD spinner fall brings pods of sipping fish to foam lines—tie on a size 16 PMD Sparkle Dun and keep your cast soft. Streamer fans: low light hours and off-color edges have been productive with black or olive articulated streamers, especially right along bankside structure and on inside bends where fish are holding close to cover. According to Montana Angler, a sculpin pattern or olive sparkle minnow is a solid bet if you’re after a big brown. Don’t ignore the terrestrial game. Hoppers are gaining momentum—yellow and tan foam patterns like a Flutter Bug or Water Walker turn heads along grassy banks. Toss a small stimulator or a foam run caddis into riffly water and get ready for an aggressive rise. The Yellowstone River to the west is also putting up solid numbers, with a mixed hatch of caddis, March browns, and hoppers, if you’re feeling like a road trip. If you’re hunting bait, small crawlers and leeches are bringing in the odd whitefish or jumbo brown where permitted, but artificials are ruling the day. Water temps are safe for trout early and mid-morning; by afternoon, fish are sliding deep or into faster current, so move with them and don’t hesitate to cover water. For hot spots, don’t miss the Afterbay section below the dam—a classic Bighorn drift with deep runs and productive seams. Another favorite is the Three Mile access, especially right at dawn. The side channels and willow-lined cuts upriver still hold sneaky fish, especially for wade anglers working soft seam This content was created in partnership and with the help of Artificial Intelligence AI.