October Fishing on the Stillwater River

October weather, stream flows, and summary

October fly fishing on the Stillwater River may serve up a few bouts of winter-like fishing conditions, but for anglers desiring solitude and time on a river before it transitions fully into winter, the Stillwater River can check several boxes. By October the peaks and plateaus of the Beartooth Mountains are covered in snow, creating a beautiful setting to cast a fly on the fast waters of the Stillwater River. 

October on this small freestone river is the month of Blue Winged Olives and big trout chasing streamers. Gone are the long, sunny days of summer and with them, other anglers occupying the next bend. October is a month for anglers who appreciate the process and the surroundings, as much as the result. 

The weather is varied—from days of bright sunshine and highs in the 70s to blizzards and highs in the teens. The law of averages rules and the average daily high temperature hovers in the low 60 degrees F. There is slightly more precipitation in October than September with an average of 1.3” and the possibility of snow increases substantially with a 1.9” monthly average. Snowy or rainy weather may seem less than ideal for fishing, but in October often the lousiest weather produces the best fishing. 

Stream flows are consistent and clear on the Stillwater River in October, averaging around 500 cubic feet per second (cfs) throughout the month. At these flows floating is very difficult above Absarokee, so walking-and-wading anglers can enjoy a river mostly devoid of rafts. However, in order to adequately fish the Stillwater River on foot, anglers need to be prepared to walk a good bit as public access points are spaced miles apart. 

For both floating and walking-and-wading anglers, October and the regular occurrence of fall-like weather means a commitment to fishing streamers for aggressive brown trout. This is the month streamer addicts relish in quick strikes and fast strips. 

Blue Winged Olives (BWOs) are the primary hatch of October. A few October caddis are spotted but they are not consistent and emerge in small numbers, usually one or two at a time compared to the thousands of insects during a BWO hatch. 

Planning to fish an October caddis hatch is more speculation than expectation. October does see a few days of sunshine and warm air temperatures above 65 degrees F, if this does happen terrestrials can become active for a brief timeframe.

October fishing: what to expect

Attitude makes all the difference when fly fishing the Stillwater River in October. The weather can vary from day to day or hour to hour and hatches can be sparse to thick, therefore anglers must be flexible. For anglers desiring to chase brown trout, they must understand that these trout can be on the chase or not. This is a month where patience and process must rule over putting fish in the net. 

On the days with the worst weather, Blue Winged Olive (BWOs) mayflies tend to hatch in rainy or snowy weather. Brown trout, especially large brown trout, are inherently more sensitive to bright sunshine in the fall. Fishing in cold, rainy, or snowy weather may not be what you find as enjoyable but armed with quality gear and a good attitude it just might pay dividends. 

Because BWOs tend to hatch mid-day, a typical day fly fishing the Stillwater River in October can begin around 10 AM. Large brown trout may be active early and the sun often hasn’t fully cracked the horizon until 8 AM, so early morning starts are not crucial. Tandem two-fly nymph rigs—with size 16 beadhead nymphs on 4X fluorocarbon tippet still catch plenty of fish in October—but this is the month for the streamer angler. 

Yellow and brown and black or brown streamers in sizes 2 to 8 are the best choices for October brown trout on the Stillwater River. Favorite tactics include dead-drifting a large streamer below a strike indicator or dragging a large streamer through a deep hole. Many anglers will also trail a smaller nymph such as a size 16 or 18 mayfly nymph, creating a two-fly rig designed to entice a big brown trout.

Dry fly anglers can target hatches of Blue Winged Olives. Most are size 16 or 18, so be sure to have plenty of parachute mayfly or Sparkle dun BWO patterns. When conditions line-up appropriately, typically a forecast for light rain or snow flurries coupled with low winds, Stillwater River trout will feed with frenzy during a thick BWO hatch.  

Where to find October trout on the Stillwater

Similar to September, trout on the Stillwater in October can be found where the food or prey are prevalent. Nymphs—mayfly, caddis, and stonefly nymphs—are active in the Stillwater River year-round. Unless a hatch of Blue Winged Olive (BWOs) mayflies is strong, trout will be found in subsurface holding lies. 

When fishing tandem nymph rigs, focus on the deeper water near shallow water, behind or in front of structure, or any place that can provide cover from predators or fast currents. If it is sunny and the air temperature hovers near 60 degrees F or higher, consider fishing terrestrials even as late as mid-October. Because a grasshopper is a large morsel of food, a hungry trout may move several feet to gobble-up a large insect. Fishing grasshoppers on the Stillwater River in October is a rarity but it does happen. 

Throughout the month, hatches of BWOs are a possibility each day. As the month grows brown trout become even more aggressive prior to fall spawning. BWO nymphs can be found throughout the river even if a hatch is not occurring. But, when a strong hatch occurs, look for trout in slower currents and “softer water” such as the inside of river bends, seams behind rocks, and slower runs below riffles. 

During October brown trout can be found in several predator hangouts—deeper water near shallow water, hiding near structure, or along a cut bank. Many brown trout will begin to spawn in October. These spawning fish may be found on their redds on shallow gravel bars. Please avoid targeting spawning trout when they are encountered.

Important October hatches

October hatches on the Stillwater River are small in scope compared to other months. Even as the Stillwater River is home to a healthy population of stoneflies, mayflies, and caddis whose nymphs are active year-round, the amount of hatching insects in October is not like it is the rest of the season. Nymphs are active, but most of the active nymphs are small Blue Winged Olive (BWOs) mayflies. 

BWOs provide the primary hatch on the Stillwater River in October. These small mayflies can hatch on any day during the month. Overcast, rainy or snowy days see the strongest emergences. These mayflies are slightly smaller than their spring season cousins. Ranging in size from 16 to 22, these insects will emerge by late-morning or early afternoon and provide a few to several hours of quality dry fly fishing or subsurface nymph fishing. 

October caddis also hatch on the Stillwater River. These bugs may be large in size—about size 8—but their hatch is sporadic. In a day of angling only a few October caddis may actually be seen fluttering in the air but committing to a large dry fly can bring the occasional opportunistic trout to the surface. 

Stillwater River fly box for October

BWO dry flies sizes 16 to 22

BWO emergers sizes 16 to 20

BWO nymphs sizes 16 to 20

October caddis size 8

Crayfish patterns sizes 2 to 8

Sculpin patterns sizes 2 to 6

Streamers in yellow and brown, black or brown sizes 2 to 6