Big Sky Anglers Weekly Fishing Report – September 5, 2019

by | Sep 5, 2019 | 0 comments

The 2019 fishing season in Big Sky Country has been a wild ride, weather-wise. Dry, stable conditions the past two weeks have been a welcome respite from the daily doses of thunderstorms and accompanying downpours that plagued June, July, and the first half of August. 

But, just when we were all starting to get pretty proud of our Chaco tans, the forecast is predicting the wild ride will continue. Cold, wet weather is set to move into the area this evening with temps dropping 20-25 degrees from what we have been seeing. Rain is in the forecast nearly every day for the next week. 

This weather adjustment is common in Big Sky Country. On most years we see the first fall storm roll through in early September. Many years it brings with it the much anticipated end of fire season, but 2019 has, luckily, not been one of those years as we have enjoyed a smoke-free summer all the way through Labor Day Weekend. 

The first fall storm brings with it a change in the seasonal hatch cycle, and fishing. It’s time to shove those terrestrial boxes aside and start thinking about fall hatches. Bugs aren’t the only critters to activate with a change in the weather. Brown trout all across the area will click into fall gear with cooler temps and scuzzy skies. 

The timing of this year’s first fall storm couldn’t be better for our Third Annual Trout Spey Days, which are coming up next Friday and Saturday, September 13&14. Several days of inclement weather leading up to the event will prime local fisheries like the Madison in YNP with the first good push of migratory fish. 

If all this talk of scuzzy weather gets you down, don’t despair. There’s a good to great chance of Indian Summer making an appearance directly following this cycle, and those are traditionally some of the most beautiful days of the year. So hang in there, embrace the change in weather, and enjoy this first taste of fall. 

Read on to see our take on this week’s fishing, and check out the links below to stay current on area forecasts and flows. Stay tuned as we report each week on hatches, flows, weather, and more. For the most up to date info stop by the shop, give us a call, or drop us a line.

West Yellowstone Forecast

MT Streamflows

ID Streamflows

Henry’s Fork

This season’s first fall storm will produce good dry fly fishing situations on the Railroad Ranch section of the Henry’s Fork as well. Beatis, Pseudos, Mahoganies, and, in places, PMD’s should all be active. Don’t forget to keep a honey ant or small hopper in the line up for those extra-snotty targets. 

Cooler weather will be good for the lower river too. Look for Baetis hatches in the afternoons, and consider pulling a streamer around in the mornings and evenings, though stick to the bigger, less weedy runs. 

If you’re trying to scratch that autumn streamer itch, and the weeds in the lower river have you down, check out Warm River to Ashton. You’ll find fewer weeds, and maybe a few respectable browns. 

Yellowstone National Park

The Northeast Corner

Fall weather will bring some exciting changes to the fishing on waters like the Lamar River and  Slough Creek. Unfortunately, rain will wreak havoc on the water conditions on the Lamar and downstream to the Yellowstone River. Slough will remain clear, and fishing there should benefit from the addition of fall hatches like Baetis, and Drakes. Keep a close eye on flows if you’re planning a trip to this part of the park, or better yet, give us a call or swing by the shop for the latest info.

The Yellowstone River

This week’s rain event will likely bring color to the flows on the Yellowstone in the canyon below its confluence with the Lamar River. However, the upper stretches in the caldera will remain clear, and scuzzy weather can have a tremendous impact on this bug factory. Expect to see numerous, different mayflies on the water in the late mornings and afternoons here. Baetis, PMD’s, Heptagenia and several more obscure bugs could all be present. Overcast skies will prove difficult for sight fishing. So, be sure to watch for rises, and limit blind fishing. Although there are still a good number of fish in the river, they are very migratory within the river, and more fish are dropping back to the lake every day. 

The Gallatin River  

The Park stretch of the Gallatin can see great Baetis hatches on foul weather days in September. As always here, expect to see the best hatches and fishing in the afternoon. 

The Firehole and Madison (in YNP)

These two perennial fall favorites have been quietly coming into shape as the days continue to get shorter and the nights cooler. A shift in the weather is all that we were missing for the fishing to truly turn on here. Look for some of the first consistent hatches of fall Baetis to get rolling on the coldest, wettest days. And, don’t forget to downsize your Baetis imitations from the relatively giant size #18’s and #20’s that you were using in the Spring to a diminutive size #22. Like all members of the Beatidae family, the fall Baetis (Blue Winged Olives) are multi brooded with the Spring’s hatches rearing the individuals that hatch in the fall, and each generation is smaller in size. 


Madison River

Terrestrial fishing on the Fifty Mile Riffle has been nothing short of outstanding this summer. Sadly though, all good things must come to an end, and this week’s cool wet weather will put the kibosh on hopper and ant fishing for the foreseeable future. Who knows if this will be full knockout punch, or if we will get more rounds to slug it out when Indian Summer arrives. Time will tell. 

In the meantime, we get to enjoy some fun fishing with fall hatches of Baetis mayflies and Rhyacophila caddis. Look to the walk-wade stretch from Quake Lake to Lyons bridge for some dry fly fishing in the afternoons. These will be technical, challenging sessions with selective trout feeding on small, size 22, Baetis and Pseudos. Hunt for your targets, and watch for ultra-sneaky rises, many times in water only inches from the bank. 

This is also a good time to dust off the streamer rod, or just clip the hopper off the end of your six weight and tie on a Copper Zonker or sculpin imitation. 

Hebgen Lake

Just like the terrestrial fishing across the area, the gulper fishing on Hebgen will take it in the shorts this week with the return of unsettled weather, but don’t give up on the season just yet. If good conditions return after this period of scuzzy weather, we could see some more great gulpering as Indian Summer days are often the calmest of the entire year. 

Henry’s Lake

Autumn fishing on stillwaters can be incredible… if conditions allow the angler to get onto the water for meaningful periods of time.  The first winds and cold nights of September bring about major change in the stillwater environment, and especially on the shallower, weedier lakes like Henry’s.  Water temps drop back into favorable ranges for the trout.  The winds reoxegenate the shallows.  And the seasonal change begins the dieoff of the shallow water weeds, exposing vast quantities of food that were hidden from the trout in August.  Find the weed edges, and follow them in towards shore as the month progresses.  Fall is big fish time on Hank’s, so up sizing the tippet isn’t the worst of ideas.