San Juan River Fishing Update September 2025

September is one of the very best times to book a guided fly fishing trip on the San Juan River in New Mexico. The crowds thin out, the weather cools, and the trout feed with urgency as fall approaches. If you’ve been thinking about making the trip, this is the month when everything comes together. The San Juan is flowing clear, cool, and stable right now, which means perfect conditions whether you’re stepping into the water to wade or floating with one of our guides. Hungry trout are spread throughout the river and feeding actively, giving anglers incredible opportunities all day long.

In the mornings and evenings, trout slide into the riffles and shallow water to feed, offering some of the best sight-fishing and dry fly chances of the season. Midday, when the sun is high, fish tuck back into the deeper runs and pools where nymph rigs dominate. This is where our guides excel—adjusting timing, flies, and techniques to keep you connected and in the fish all day. September is a technical month, but that’s what makes it so rewarding when the rod bends.

Flies you’ll want in your box this September:

• Midges (sizes 22–26) in black, olive, and brown
• Baetis nymphs like RS-2s and Pheasant Tails
• San Juan Worms and egg patterns as attractors
• Blue-Winged Olives, Parachute Adams, and Griffith’s Gnats on cloudy afternoons
• Bunny Leeches and small baitfish patterns for streamer eaters

Recommended gear for the San Juan River in September:

• 9–10 foot 4-weight rod (perfect for both dries and nymphing)
• 9ft 6wt or 7wt for streamer fishing
• Floating line with long leaders for nymph rigs
• 5x–6x fluorocarbon tippet for clear water stealth
• Monofilament leaders when fishing dry flies

September combines everything we love about guiding on the San Juan River: crisp desert mornings, beautiful canyon scenery, and trout that are feeding aggressively before the cooler months ahead. It’s one of the finest times to fish here.

Whether you want to learn the subtle art of fishing tiny midges, experience the thrill of watching trout rise on dry flies, or strip streamers for a chance at a true San Juan trophy, we’ve got you covered. About Trout Fly Fishing specializes in making your trip to the San Juan not just successful, but unforgettable. September only comes once a year—don’t miss it.

If you made it this far you may enjoy Mark McGrath, of the band Sugar Ray give our September Update