October Fishing on the Jefferson River

October weather, stream flows, and summary

Of all the months of the angling calendar for fishing the Jefferson River, October is the most consistent and most popular. During this final month of the angling calendar, anglers can experience some great dry fly fishing—with Blue Winged Olive (BWOs) mayflies and some October caddis. Plus, many of the river’s largest trout come to hand in October as the river sees a dedicated influx of hard-core streamer anglers desiring a Jefferson River trophy-sized brown trout. 

Water temperatures rarely top 60 degrees F, which means trout are actively feeding more than they are not. October weather is diverse with days of sunshine, showers, and possible snow. With highs in the 60s to snow storms and highs in the teens, anglers fishing the Jefferson River in October should prepare for all four seasons any day of the week. 

The average daily high temperature is in the high 50 degrees F. There is slightly less rain in October than September with an average of 1.1” and the possibility of snow increases with an average of 0.2” inches. Quality fishing opportunities can occur in these variable weather conditions, and often the lousiest weather produces the best October fly fishing. 

In October hatches of BWOs can be thick on the Jefferson River. A few October caddis are also 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. But it is the river’s population of brown trout that attracts most anglers in October as they hope to target these predatory fish with streamers. 

October on the Jefferson River has a dedicated following of anglers. With less crowds, cooler water temperatures, aggressive brown trout, and the prospect for strong hatches of BWOs, the Jefferson River in October can serve up unique fly fishing for anglers desiring something less-known and less-crowded than nearby rivers.  

October fishing: what to expect

Similar to late September, sun, rain, and snow can all happen on the same day. As the weather in October also becomes colder and days are shorter, the prospect of large brown trout increases. If targeting brown trout is not as desired as matching a hatch, the Jefferson River in October can check that box. 

Hatches of Blue Winged Olive (BWOs) mayflies can be thick on the Jefferson River. During October it is always a good idea to have a favorite size 16 mayfly dry fly such as a parachute Adams plus several size 4 or 6 yellow, brown, or olive streamer patterns. 

The Jefferson River has plenty of drop-offs and plenty of submerged structures—both are home to predatory brown trout. In October streamer anglers should fish large articulated streamer patterns in size 4 and 6. Tandem nymph rigs with size 16 and 18 beadhead mayfly and caddis nymph patterns can also produce fish. 

On any section of the river, a typical day fly fishing the Jefferson River in October begins in the mid-morning. If BWOs hatch they will begin around mid-morning or late afternoon. For streamer anglers, large brown trout may be active early, but the sun rises between 7 and 8 AM most mornings in October so early starts are not crucial. 

Yellow, brown, and olive streamers are the color choices for October trophy-sized trout. Most large fish are caught while dead-drifting a large streamer below a strike indicator or dragging a large streamer off the bank. 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 more selective trout. 

Where to find October trout on the Jefferson

Because water temperatures average well below 65 degrees F and the duration of bright sunshine penetrating into the water is considerably less than summer, Jefferson River trout in October can be found in a variety of locations.

Until a hatch occurs, fishing tandem nymph rigs is the most common way to catch fish. Focus on deep water near shallow water, behind or in front of structure, or any place that can provide cover from predators or fast currents. Nymphs—mayfly, caddis, and stonefly nymphs—are active in the Jefferson River year-round. Unless there is a strong emergence of Blue Winged Olive (BWOs) mayflies, trout will be found in subsurface holding lies.  

Because the Jefferson River is home to plenty of brown trout and these trout become more aggressive in October, target the usual predator hangouts—deeper water near shallow water, hiding near structure, or under or near a cut- or under-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.

When a strong hatch of BWOs 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. 

If sunshine is abundant and the air temperature hovers near 60 degrees F or higher, the slight possibility exists for a few trout to still target terrestrials. Trout may rise from deep cover for a morsel as large as a grasshopper, ant, or beetle. These large offerings may not pass by again that day. Fishing grasshoppers in October is a rarity but it does happen. 

Important October hatches

For dry fly anglers, they will delight in consistent hatches of Blue Winged Olive (BWOs) mayflies. Of all the months of the year, October sees the most consistent dry fly hatches IF conditions are perfect. Overcast, rainy or snowy days see the strongest emergence. An overcast day with light winds can mean the dry fly fishing on the Jefferson River can be reliable, bringing plenty of fish to the surface to feed, causing anglers to forget about the low stream flows and high water temperatures of late summer.

Fall season BWO 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 small-fly dry fly fishing. 

October caddis also hatch on the Jefferson River. These bugs may be large in size—about size 8—but their hatch is small in stature. It is a rare event to see an October caddis hatch on the Jefferson River, but on a sunny day it is not too rare to have a few trout smash a size 8 or 10 October caddis dry fly. 

Jefferson 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, purple, brown, olive, brown/yellow, or black in sizes 2 to 6