San Juan River Fly Fishing Report - September 20, 2026
SAN JUAN RIVER
ReportSEP 20 — 27, 2026
🌊
Flow
—CFS
🌡️
Water Temp
—
☀️
Weather
46–78°F
Mostly Clear
💧
Clarity
Clear
Check post-storm
Live USGS gauge data is unavailable for today, but recent web intel consistently puts flows near 883 CFS at a gauge height of 4.74 ft — a productive, wadeable level — with water temps around 48.7°F keeping trout aggressive and in a feeding mood; clarity is reported clear with a note to watch for any post-storm turbidity.
What's Working — Hot Flies
Olsen's Peacock Blowtorch Barbless #22 - 24
#22-24
Olsen's Hare's Ear Blowtorch Barbless #20 - 28
#20-22
Juju Baetis Tungsten #22
#22
Tungsten Tailwater Sowbug - Rainbow #10
#10
Roza's World Spain Perdigon Barbless #18 - 32
#18-20
Parachute - Blue Wing Olive #22
#22
Egan's CDC Rainbow Warrior #22
#22
Corn-fed Caddis (CDC) Tan #20
#20
Egan's Frenchie Chironomid #10
#10
Egan's Silver Bullet - Baetis #14
#14
Top Secret Baetis #16
#16
Tailwater Sowbug - Rainbow #10
#10
Hatch Chart
| Insect | Size | Activity | Prime Time |
|---|---|---|---|
| Midge (Chironomid) | 20-24 | Heavy | 9 AM - 1 PM |
| Blue-Winged Olive (Baetis) | 20-22 | Moderate | 11 AM - 3 PM |
| Caddis | 18-20 | Light | 4 PM - 6 PM |
| Sowbug / Scud | 10-14 | Heavy | All Day |
| PMD (Pale Morning Dun) | 18-20 | Light | 10 AM - 1 PM |
Best Time Window
- 7 AM - 10 AM: Pre-hatch nymphing in the deeper runs and slots with sowbug and midge patterns before the sun hits the water.
- 10 AM - 2 PM: Prime BWO and midge hatch window — watch the flats for rising fish and be ready to switch to dry flies or emergers.
- 4 PM - 6 PM: Late-afternoon caddis activity in the riffles; skitter a CDC caddis through the broken water for aggressive surface takes.
Guide's Tip
From the benchAt 883 CFS and 48.7°F, the San Juan is fishing in prime fall form — trout are aggressive and holding in predictable lies. Focus your morning sessions on the deeper runs and slots using a tight-line or indicator nymph setup with your sowbug and midge patterns set 18 to 24 inches off the bottom. As water temps peak mid-day and BWOs start trickling off, shift to the slower flats and watch for subtle risers; a size 22 parachute BWO or CDC emerger presented with a long, fine tippet (6X) will get eats from even the most selective fish. In the afternoon, work the riffles with your caddis patterns as the sun drops off the water.
Main Species
Rainbow Trout
Brown Trout
