Three Dry Flies for August on the San Juan River

August is traditionally one of our favorite months to fish dry flies on the San Juan River. It’s also one of the least windy times of the year, which can make for some great evenings spent headhunting rising trout.

With the strong summer sun, the best dry-fly windows are usually early in the morning, on an overcast day, or after about 4 p.m. as the sun starts dropping behind the canyon walls.

If I could only carry three dry flies in August, these would be it.

1. Size 14 Chubby Chernobyl

San Juan trout are still willing to look up for a bigger meal this time of year, and a small Chubby is one of our favorites.

A size 14 gives you a visible, buoyant fly that can pull fish up even when there isn’t an obvious terrestrial hatch happening. It’s especially fun when you’re prospecting likely water instead of casting to a specific rising fish.

2. Griffith’s Gnat

The Griffith’s Gnat is probably the most important fly on this list when fish start getting selective.

In the evenings, most of the insect activity we see is midges, with some baetis mixed in. When trout key in on individual midges or midge clusters, a Griffith’s Gnat can be hard to beat.

We’ll fish them in a wide range of sizes depending on what the trout are doing—from larger cluster-style patterns like a size 10 Dead Chicken all the way down to tiny size 22s and 24s.

When you see fish consistently rising but refusing everything else, this is usually where I start.

3. Size 24 Parachute Adams

Old faithful.

For whatever reason, even during heavy midge activity when San Juan trout get extremely picky, a tiny Parachute Adams continues to fool fish.

A size 24 is a staple for us, and there are times when dropping all the way to a 26 can make the difference.

It doesn’t perfectly imitate every insect on the water, but it has the right profile to consistently get eaten—and sometimes that’s all that matters.

August Dry-Fly Fishing

August evenings on the San Juan can be some of the most enjoyable fishing of the entire summer. The wind settles down, the sun starts disappearing, bugs begin moving, and trout that spent the middle of the day tucked away start looking toward the surface.

Whether you’re fishing with us or spending an evening headhunting on your own, these are the three dries I’d want in my box:

Size 14 Chubby Chernobyl
Griffith’s Gnat — sizes 10 through 24
Size 24 Parachute Adams

Keep an eye on the shadows, watch for noses, and don’t be afraid to stay until the sun disappears.