Missouri and Yellowstone trout windows open as fall cools

What's next

Expect the cool, stable water to hold through the weekend unless a storm pushes flows up. With temperatures in the upper 40s, the best fishing should come in the warmer part of the day, roughly late morning through mid afternoon, when insects are most active.

Per Flylords Mag, autumn is streamer season. Trout feed heavily on baitfish and sculpins before winter, and drifting streamers in early fall is a productive way to find the bigger fish. Flylab (Substack) describes small dries and stiff hackles as the pattern for this time of year, which fits for quieter midday windows on slower water.

The First Quarter moon puts moderate light in the evening sky. Early morning and the last hour before dark are worth planning around if you want to fish low-light streamer water.

Context

Mid October is typically a transition period on Montana's big rivers. Flows have usually dropped from summer levels, water temperatures sit well below the stress range, and brown trout move toward spawning behavior, which tends to make them more aggressive and more exposed. Anglers generally rotate between streamers on cloudy or rainy days and small midge or baetis patterns when the sun is out.

This timing is about on schedule for the season. Seasonal closures on spawning reaches are common this time of year, so confirm the regulations for the section you plan to fish.