Flathead trout shift to fall patterns as water cools

What's biting

What's next

With a New Moon today, expect low light overnight and a quiet start to the week. Trout often feed best on overcast afternoons this time of year, so plan around cloud cover rather than bright midday sun. If the cooling trend continues, the 57°F reading should drift lower over the coming days, which tends to keep Brown Trout and Brook Trout active and moving toward fall staging water.

Start with small baetis and midge patterns fished near the bottom. Caddis Fly (OR) lists the Perdigon as a hot fly this fall, a streamlined, heavy nymph that gets down quickly in strong current. Flows of this size call for extra split shot, so build your rig to reach the strike zone, then trim weight if you are hanging up. Mainely Fly Fishing notes that trout in New England were already showing spawning colors in late summer, a reminder that Brook Trout and Brown Trout get more aggressive and territorial as autumn advances. Fish with care around any spawning beds and keep fish wet when releasing them.

Mornings and the last hour of daylight are the windows worth planning around, when bug activity and fish movement tend to peak. Check state regulations and any fall closures before heading out.

Context

Mid-October is typically the heart of fall for western Montana rivers and big lakes. Water that ran warm and low in summer has cooled, hatches have narrowed to small mayflies and midges, and fish put on weight ahead of winter. A reading of 57°F at this point in the season is a healthy mark, and flow at this level is on the generous side for the date. Streamers and egg patterns gain importance from here as spawning activity builds.