What flies are hatching on the Boulder River right now?

Current and seasonal hatches on the Boulder River include Salmonfly, Golden Stone, Caddis. Use the AI Hatch Advisor on this page for a live, temperature-aware recommendation.

What's the current flow on the Boulder River?

The Boulder River is running at 4,030 CFS at the Near Big Timber gauge. Readings update every 15 minutes from the USGS Water Services API.

Is the Boulder River fishable today?

Boulder River is outside its fishable window right now. Flow is 4,030 CFS at the Near Big Timber gauge. Check back when conditions return to the normal range.

Boulder River Fly Fishing Conditions

Live Conditions

Boulder River — Near Big Timber

Unfishable

4,030CFS

Discharge

3.12ft

Gauge Height

70.7°F

Water Temp

Updated 1 hr agoView on USGS ↗

7-Day Flow

→ Stable

RisingFallingStable

24-Hr Pressure

24.23 inHg · → High/stable

Falling (good)RisingHigh/stable

Voluntary Catch-and-Release Advisory

Water temperature is at or above 65°F. At these temperatures trout are physiologically stressed and have a higher post-release mortality rate. Consider waiting for cooler conditions — early morning or evening — or choosing a tailwater with regulated temperatures.

Local Weather

58°FClear sky

Wind 9 mph24.23 inHg Low & stable

Tough conditions — fish deep

Today

☁️

Overcast

84° / 65°

Tomorrow

☁️

Overcast

65° / 51°

Tue

☀️

Clear sky

67° / 44°

Wed

☀️

Clear sky

80° / 52°

Cold front incoming — go deep with nymphs, surface activity likely slow.

Weather by Open-Meteo · No API key · Updated every 30 min

What should I fish today?

⚡ AI

AI-powered recommendation using today's live flow, temperature, and hatch data.

2

Time of Day

Using: 4,030 CFS · 70.7°F · PMDs continue. Hopper season peak

What should I pack?

Rod, flies, tippet, and safety gear specific to today's Boulder River conditions.

🪰 Hatch Calendar

Boulder River · August · Late Summer

Full calendar →

🟡 Approaching — within 5°F of trigger range

Caddis

Select month

JanDec

PMDs continue. Hopper season peak (size 8-12). Caddis evenings. Cool mountain water stays productive. Pocket water through the canyon at its best.

PMDCaddis

🟢 Active · 🟡 Approaching · ⚪ Seasonal only

River Map

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USGS Gauge (click for site ID)Fishing Access / SectionScroll to zoom disabled — use map controls

About Boulder River

Small classic Montana freestone draining the Absaroka-Beartooth Wilderness south of Big Timber. Pocket water and meadow runs full of wild trout — a low-pressure alternative to the nearby Yellowstone and Stillwater.

SalmonflyGolden StoneCaddisPale Morning DunHopperBlue-Winged Olive

Regulations

Standard Montana trout regulations apply on the Boulder; cutthroat and brown trout are present in the upper reaches. Montana fishing license required. Verify current regs at fwp.mt.gov before fishing.

Learn More

Guides to help you fish Boulder River with more confidence.