Fishing Season: Year Round (Prime: April 1 - November 31)

Bighorn River - MT

Fishing Outlook & Conditions

Water Temp:

52

Forrester's Big Horn River Resort's Tip of the Week

Position yourself in the flat water below the riffles at first light for the Trico spinner fall — this is the best dry fly fishing of the season right now. Drop down to 5X or 6X tippet and add an extra 12 inches to your leader to eliminate micro-drag in September's clear low water. In the morning, start with Trico spinners on the surface, then transition to deep nymphing with sowbugs and scuds as the morning progresses. Watch for Blue Winged Olive hatches on overcast afternoons in the softer water. Once you find a pod of feeding fish in a lane, stay put — the fish are grouped and consistent right now. As the month progresses, start throwing streamers along the undercut banks — the big browns are staging for fall and are becoming increasingly aggressive.

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Map of Bighorn River

Water Flow Data

Orvis-Endorsed guides nearby

Bighorn River Resort

5-Day Outlook as of 9/8/26

ONE-WEEK FORECAST Monday September 7: 79°F, sunny, 0% chance of rain. Tuesday September 8: 75°F, 15% chance of rain. Wednesday September 9: 79°F, sunny, 0% chance of rain. Thursday September 10: 88°F, sunny, 0% chance of rain. Friday September 11: 70°F, 15% chance of rain. Saturday September 12: 67°F, 15% chance of rain. Sunday September 13: 70°F, 15% chance of rain. Overall a beautiful September week with comfortable temperatures and some overcast days mid to late week — perfect conditions for BWO hatches and Trico spinner falls. The cooler weekend days will be excellent fishing.

Techniques & Tips as of 9/8/26

Start each morning with Trico spinner falls — position yourself in the flat water below the riffles at first light and watch for subtle sipping rises. Use 5X or 6X tippet and a long leader for drag-free presentations in September's clear low water. Through mid-morning transition to deep nymphing with sowbugs and scuds set 4 to 5 feet under an indicator. Keep everything deep and drifting clean — if you are not occasionally ticking bottom add weight before changing flies. On overcast afternoons watch for Blue Winged Olive hatches in the softer water along the banks and in the tailouts of long flats. A CDC Baetis or Parachute BWO on a drag-free drift will find fish that have moved up to feed. As September progresses add streamer fishing to your rotation — slow strip a sculpin or woolly bugger along undercut banks and deeper runs in the morning and evening. The big browns are staging for fall and are becoming noticeably aggressive. Once you find a pod of feeding fish stay on that water — they are grouped and consistent right now.

Local Species Available Year Round (Prime: April 1 - November 31)

  • Fish Icon

    Wild Rainbow & Brown Trout

Forrester's Big Horn River Resort's Recommended Fly Patterns

"Must-have" fly fishing patterns in descending order of importance:

Name: Colors: Size(s):
TH Zebra Midge Black 18-20
Bead Head Brassie™ N/A 18-24
Blue Winged Olive N/A 16-18
RS2 18-20
Tungsten Jig Bugger White & Black 12-18
Midge Black 16-20
All Day Wood Multi 14
baetis black 16-22
Ray Charles Grey 14-16
Pinky Pink 16-18

TH Zebra Midge

Designed for success in stillwater, the TH Zebra Midge fly pattern imitates chironomids, a trout diet staple.

Forrester's Big Horn River Resort's Recommended Gear

Description: About Bighorn River

The most easterly of Montana's fine rivers, the Blue Ribbon waters of the Bighorn, is also the finest in terms of numbers of fish. With nearly 2,500 fish per mile at an average of 19+ inches, catching 20 to 24" browns and rainbows every day, it is no surprise the river is known for its fantastic fishing and cold water. The section of the Bighorn in south eastern Montana is actually the last section of the river. Beginning when it flows out of the Wind River drainage out of Wyoming. The Bighorn's course is as unique as its fishing. After flowing through much of Wyoming the river flows into Bighorn Lake which is created by Yellowtail Dam. Yellowtail is a 525 foot concrete dam, that fills a remarkable 71 mile “breath taking” canyon and offers recreation for boating enthusiasts. But it isn't until the river releases from the bottom of the dam that the fishing becomes world-class. This clear and cold release creates nearly 30 miles of prime wild trout habitat. With an average of 50 degrees the aquatic bug life is truly a biologists dream. Also to mention the installation of the Afterbay Dam 1 mile below Yellowtail Dam, takes the fluctuation out of this hydroelectric dam, which is prominent in tail water fisheries. The result is constant flows year round. As mentioned the Bighorn is arguably one of the finest streams in the state, and in the world. The high fish count per-mile is one thing, but the potential for a lifetime trophy brown or rainbow trout is very good on this river. Browns average around 16 inches and rainbows average just a touch larger. Hatches are prolific the entire year and because the Bighorn is in the southeastern corner of the state and at a lower elevation than many Montana streams it can, and does fish well, the entire year. During the different hatches it is not unusual to have 10-20 fish with in easily casting distances. The flies of choice are on the small size 16-20’s with tippets ranging from 3x-6x fished with 8 ½ - 9 foot 4-6 weight rods. With Montana's stream access law, the Bighorn remains a float-fishers rivers. Using a drift boat, or other floating craft is the most effective way to fish the Bighorn. Bank or wading anglers are limited by a few state owned accesses and gaining permission from landowners is difficult, mainly because it flows through the Crow Indian Reservation. The Bighorn is the ideal river for anyone wishing to head to one destination and intimately fish one river. However, it is important to note that the Bighorn is still a natural fishery. Even though there are over several thousand fish per mile doesn't mean that fish are pushovers, quite the contrary as the Bighorn is still a technical river that requires some local knowledge and patience to fish successfully. Fortunately, as isolated as the Bighorn may seem, there are a few quality lodging options located near the premier top 3 mile section of the river. The river averages 150-250 feet in width with flows average in the 2000-3000 Cubic Feet Per Second (CFS) range. Prime flows for the Bighorn range from 2,000 to 5,000 CFS. With broad riffles followed by deep pools. The landscape is equally impressive with rolling plains, sparsely places cottonwoods and willows are the backdrop for this section. Gravel and grass islands, with the oh-so inviting side-channels are found throughout the river. These islands create unique riffle corners, side channels and drop offs that always yield some great fish and great memories. The sections to float are Afterbay to Three Mile access, which is the most popular and premier section of the river. The second section is Three Mile to Bighorn, which is about a ten mile float, which offers great fishing in a more secluded setting. The last section, Bighorn to Mallards, is the start of the motorized craft area. That does somewhat retract from the solitude of the fly fishing experience. The fish numbers are smaller due to the water quality by tributary run off as well as irrigation returned ditches on this lower section of the river. The most popular float is Afterbay to Bighorn access. Billings Montana is a the nearest major city which is a 90 minute drive and nearest major airport with commercial service. There is a small airstrip in Ft. Smith that can accommodate private planes. The Bighorn truly is one of the great fisheries in the world. If offers a fly fisherperson the experience of a life time. This river always lives up to the legendary status that it has become.

Nearest Airport:

Billings Logan International Airport (BIL)

Hatches:

Trico — peak spinner falls at first light, August through September Blue Winged Olive (BWO) — building on overcast afternoons, fall is arriving Midge — reliable all day, especially mornings Caddis — evenings along the banks, tapering off from August peak PMD — still showing on overcast mornings, winding down for the season

Best Time to Fish:

Morning through Evening — peak action 11am-2pm PMD hatch and 6:30-8:30pm spinner fall Best stretch:

Best Stretch:

Afterbay to 3 Mile-upper river, crystal clear water, excellent dry fly and nymphing water 3 Mile to Bighorn -— lower sections, slightly more visibility, excellent streamer water as browns begin staging for fall

Best Access:

Afterbay — upper river, excellent wade and float access, prime dry fly water 3 Mile — most popular access point, excellent for both wade and float fishing Bighorn FAS — lower river access, good for streamer fishing as browns stage for fall