The best Montana fly fishing in September by MT Angling Co.
By angelamontana

Posted: September 16, 2021

September is one of the best months to fly fish in Montana. Fall is in the air and with it comes perfect conditions for fly fishing. The strong summer hatches of terrestrials continue often through the end of the month, and good hatches of caddisflies and mayflies can be expected by the middle of the month on the Missouri River, Yellowstone River, and Madison River.

September flows on our rivers are ideal for both float fishing and wade fishing trips. Anglers will find solitude and productive days on the water on all of our local Montana rivers. The fly fishing in September in Montana is rewarding for beginner and seasoned anglers alike, making it the perfect time to start or build on your Montana fly fishing journey.


  • The Missouri River offers some of the most consistent and productive fly fishing of the year. Strong hatches of caddisflies and mayflies mean great dry fly fishing and nymphing. By the end of the month streamer fishing can be equally as productive and produce some of the largest trout of the year.
  • On the Yellowstone River and Madison River near Bozeman, MT anglers can expect some of similarly great fly fishing with excellent hopper and dry fly fishing through the end of the month.
  • The crowds and pressure of summer disappear in September and anglers will find wide open rivers and solitude.

What to Expect in September

Anglers fly fishing in Montana in September can expect consistently great fly fishing opportunities on all of our local waters. Fall weather generally sets in by the middle of the month and anglers can expect cooler mornings and hatches coinciding warm afternoons. Flows on our rivers are down from their summer highs making both float and wade fishing productive. Anglers can expect to have success dry fly fishing, nymphing, and streamer fishing throughout the month.

On the Missouri River near Craig, MT anglers can expect good conditions from the Dam down to Cascade. Angling pressure on the Missouri River is much lower in September than the summer months of June and July and anglers can expect to float the lower reaches and see few, if any, other anglers. Aquatic vegetation growth generally peaks early in the month and can be frustrating at times, but generally does not significantly interfere with fly fishing once an angler learns to fish around and on the edges of the weed beds.

On our freestone rivers in Bozeman, MT anglers can expect unmatched consistency in September. Water temperatures and flows are ideal and stable making for great fly fishing from start to finish on a daily basis. Wade fishing, even on our larger rivers, can be productive and a nice change of pace for anglers that spend the majority of their time float fishing.


Where to Fly Fish in September

Our Montana fly fishing guides recommend anglers fly fish the rivers near Bozeman, MT through the 15th of the month and the Missouri River and other nearby streams through the end of September. This positions anglers to enjoy the best fly fishing throughout the month, where and when each river is at its best.

The Yellowstone River, Madison River, and Jefferson River near Bozeman all offer great dry fly fishing through the middle of September. The hopper fishing continues to produce consistent results and dry dropper fishing can be excellent. Wade fishing in Yellowstone National Park in the Lamar Valley on the Lamar River, Soda Butte Creek, and Slough Creek is also productive with wild cutthroat trout keying in on terrestrial offerings including hoppers, beetles, and ants.

By the 15th on the month, the excellent September fly fishing on the Missouri River peaks and there is nowhere better to fly fish in Montana than the Mighty ‘Mo. The combination of strong hatches, low pressure, and ideal flows make for some of the most fun and productive fly fishing of the year. The rainbow and brown trout in the Missouri River are some of the largest in Montana and after a full season of feeding they reach their peak size and strength by the end of the month.

September Fly Fishing Tactics

One of our favorite things about fly fishing in Montana in September is the variety of tactics anglers can employ and expect to produce trout in hand. A bunch of different ways to get it done: dry fly fishing, nymphing, streamer fishing, soft hackles, dry-dropper, euro nymphing, trout spey, and the list goes on. For anglers that enjoy getting out of the boat and wade fishing there is probably no better month than September. The ideal flows and conditions allow our trout to spread out and actively feed in all water types. Expanding your angling horizons to new water types will often produce great fishing.

On the Missouri River strong Hatches of #14-16 tan caddis, #8-12 october caddis, #20-22 BWOs, and #10-14 callibaetis make for some of the best dry fly fishing of the year. Sight fishing and blind fishing will be productive. Nymphing on the upper river with shallow nymphing techniques can make for some of the most action of the year. Fishing a #14-16 caddis nymph followed by small may fly nymphs, midges, and sowbugs will be effective most days. Streamer fishing with #4-10 baitfish imitations and buggers heats up by the end of the month and the biggest brown trout in the river become aggressive feeders. The nearby Blackfoot River also fishes well throughout the month of September and offers classic western dry fly fishing for wild cutthroat, rainbow, and brown trout.

On the freestone rivers in Bozeman, MT hopper fishing and hopper dropper fishing will remain productive throughout the month of September. Warmer days are generally best and anglers should consider fishing smaller dry flies including parachutes, caddisflies, and #14-18 attractors on cooler days. Nymphing can be very productive with #12-16 attractor nymphs and streamer fishing with smaller buggers can also be effective. Wade fishing side channels and main river shelves and drop offs is always a good call in September.


September Fly Fishing Trips

Montana fly fishing trips in September offer anglers consistently great fly fishing from both our home base in Bozeman, MT as well as our Missouri River Basecamp. We recommend anglers interested in custom multi-day trips consider fishing at both: spend a few days in Bozeman enjoying the fly fishing on the Yellowstone and Madison Rivers followed by a few days fishing on the Missouri River and Blackfoot River near Craig, MT. Our Montana fly fishing guides feel the fly fishing on all of our rivers is perfect for both veteran anglers as well as beginner anglers. Strong hatches throughout the month make for fun and rewarding days on the water.

For anglers interested in streamer fishing for trophy trout, we recommend booking your trip during the last 10-days of the month on the Missouri River. This window consistently offers some of the best streamer fishing of the year. Anglers willing to fish hard will be rewarded.

Our recommendation for all anglers booking trips in September is to plan on fly fishing the rivers near Bozeman the first half of the month and the Missouri River and other nearby rivers in Craig, MT during the second half of the month. We offer a wide variety of trips covering both regions and work with experienced and professional fly fishing guides that will work hard to make your next trip, your best yet.

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