Bighorn River Fly Fishing Report - September 13, 2026

Fly Fishing Report

BIGHORN RIVER

Report
SEP 13 — 20, 2026
🌊
Flow
1850CFS
Bighorn R bl Yellowtail Afterbay Dam nr St. Xavier
🌡️
Water Temp
Updated 2026-09-12
☀️
Weather
44–81°F
Partly Cloudy
💧
Clarity
Clear
Check post-storm
Flow is running 1,850 CFS out of Yellowtail Afterbay Dam with a gauge height of 60.18 ft — up slightly from last week but still in excellent shape with clear water and strong fish activity. Sunday's high of 81°F with mostly sunny skies sets up a classic afternoon dry-fly window before a possible rain push Sunday night.
Best Time Window
  • 6:30 AM - 9:00 AM: Low-light streamer and nymph bite along undercut banks and deeper runs before the sun gets high.
  • 10:00 AM - 1:00 PM: Morning PMD and midge nymphing in riffles and tailouts; watch for early risers in flat water.
  • 1:00 PM - 5:30 PM: Prime dry-fly window as caddis hatch intensifies with afternoon warmth; focus on seams and weed-edge rises.
Guide's Tip
From the benchWith flow up to 1,850 CFS and warm afternoon temps pushing toward 81°F, the best dry-fly action will develop between 1 and 5 PM as caddis get active — position yourself in shallower runs (2-4 feet) and watch for rising fish along current seams near weed edges. For nymphing, set your indicator to fish the bottom at 1.5x the water depth and focus on the transition zones where fast water dumps into slower pools. Get your streamer time in early — the low-light window before 9 AM and the cloud cover ahead of Sunday night's rain system are prime for big browns chasing sculpin patterns along the banks. With a possible rain push after midnight Sunday and stiff WNW winds Monday, plan your best fishing for today's afternoon window.
Main Species
Brown Trout
Rainbow Trout
Mountain Whitefish
Report generated September 13, 2026 — Next update: September 20, 2026