Yellowstone trout turn to streamers as fall cools the water

What's next

With water in the low-to-mid 40s, expect fish to hold in softer, deeper seams and feed hardest in the warmest part of the day. Late morning through mid-afternoon is the window worth planning around, once the river has picked up a few degrees from the overnight low.

Per Flylords Mag, drifting streamers rather than stripping them can draw strikes from fish that follow but refuse a fast retrieve. Pair that with small nymphs and midges for slower water. Trout Unlimited's TROUT tip is useful on foggy, cold mornings too: if a cast lands off the feeding lane, let it ride rather than ripping it away and spooking the fish.

Watch flows over the next few days. Stable discharge keeps fish predictable, while a rain bump would push them tight to banks and slower edges. Per MT FWP Fishing News, spawning closures on some rivers began October 1, so check current regulations for the stretch you plan to fish before you go.

Context

Mid-October is late fall for southwest Montana. Water temperatures have dropped well below summer highs, hatches have thinned to small midges and the occasional baetis, and trout are packing on calories before winter. Brown trout spawning activity typically peaks around this time of year, so wade carefully and avoid walking through gravel redds. Crowds also thin considerably compared with summer, which makes this a favorite stretch of the calendar for anglers who like to fish with some solitude.