Late Season Yellowstone River Fishing Report - Hoppers, Streamers, and Shifting Skies

Artificial Lure here with the Yellowstone River fishing report for Sunday, September 21, 2025. If you’re tuning in from Livingston down through Paradise Valley, let’s get you dialed in for a late-season session you won’t forget.

Weather’s the first thing anglers are talking about today. According to the National Weather Service, sunrise rolled in at 7:09 AM and sunset’s set for 7:22 PM. You got about twelve hours to work with. Don Day’s local forecast calls for partly cloudy skies this morning, turning mostly cloudy as some rain showers and possible thunderstorms chase the valley by mid-afternoon. Highs will sneak up into the low 60s, while the breeze out of the southwest is steady at about 10 to 15 mph. All in, expect some afternoon chop on the water and don’t forget the rain jacket—once we hit the late day, the weather could shift on a dime.

Tidal influence isn’t a factor here—the Yellowstone’s a freestone river, flowing wild year-round. Water temps are drifting lower with the cold nights, making prime trout conditions according to the latest Spreaker fishing report. Visibility’s solid, and the river’s running clear through the Paradise Valley stretch—that’s got the browns and rainbows moving.

Fish activity has been excellent during the afternoons. Montana Outdoor’s September 18th report says the mid-to-late day window is producing the best bite as the water warms. Hopper action is still hot! Those big terrestrials are getting hammered by rainbows and cutthroats along grassy banks and undercuts. Mornings and evenings are slower; when the water’s coolest, you’ll want some patience or get creative with patterns.

Recent catches are showing off plenty of healthy fish. Anglers have been reporting solid numbers of rainbow trout in the 14-18 inch range, with the occasional cutthroat and some brown trout mixed in. Paradise Valley spring creeks like DePuy’s and Armstrong’s are giving up a few 20-inchers to persistent anglers. Streamers are enticing a few aggressive browns pre-spawn, particularly on cloudy afternoons—Montana Outdoor says dark streamers like olive or black Woolly Buggers have landed the most browns.

Best lures and bait for today? I’d tie on a hopper dropper rig with a size 10 Morrish Hopper and trail it with a small beadhead Copper John or Lightning Bug. If clouds roll thick or that afternoon shower hits, switch to small streamers or dead-drifted stonefly nymphs. Yellow, tan, and pink hoppers are consistent. If the bite gets picky, drop down to a size 16-18 parachute Adams or purple haze. Don’t forget a few olive sculpins if you want to tempt those bigger browns sulking in the deeper runs.

Hot spots you should check out today:
- Just below Mallard’s Rest: Deep buckets and grassy banks, lots of hopper eats and streamer chases.
- Carbella Access: Shallow riffles meeting deep seams, perfect for working terrestrials and nymph rigs.
- Livingston town stretch: Rainbows still abundant; clear water means sight fishing is excellent.

Wildlife is out and about—keep an eye open for wandering grizzlies along the riverside, as reported by Cowboy State Daily just last week. Don’t let it spook you, but definitely mind your bear protocols and stay aware.

That wraps up the fishing conditions for the Yellowstone River this Sunday. Weather’s shifting, but the fish are still in the mood if you hit the sweet spot this afternoon. Thanks for tuning in—be sure to subscribe for your next fishing report, and tight lines out there!

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