July is prime time for fly fishing across the country. With warm water temperatures, long days, and active insect hatches, anglers have plenty of opportunity to match the hatch and land some memorable fish. But depending on where you’re casting—from an East Coast freestone stream to a cool Western tailwater—the best flies for the job can vary greatly. After a little research, some conversations with a few guides and checking our own notes-here’s a breakdown of top fly selections for four iconic rivers across the U.S., one from each major region: East, South, North, and West.

1. East Coast: The Delaware River (New York/Pennsylvania)

This year has been unusual with the high heat, and heavy rains on the east coast but the Delaware River still produces some amazing fish. Known for its wild brown and rainbow trout and technical dry fly fishing. July can be tough due to finicky fish—especially in the Upper Delaware.

Best Flies for July:

• Sulphur Comparadun (#16-18): The tail end of the sulphur hatch can still be productive in early July, especially during late afternoon.
• Blue-Winged Olive (#18-22): BWOs are dependable throughout the summer, especially on overcast or cooler days.
• Rusty Spinner (#16-18): For evening spinner falls, this is a must-have pattern.
• Caddis Emerger (#14-16): A versatile pattern for those in-between hatches.

Tip: Focus on mornings and evenings for dry fly action. Midday nymphing with small pheasant tails or zebra midges can save a slow day. If there is light rain try using ants and beetles.

2. Southern U.S.: The South Holston River (Tennessee)

The SoHo is a tailwater that stays cool all summer, offering consistent insect activity even in the heat of the South. It’s known for its prolific sulphur hatch and dense fish population.

Best Flies for July:

• Sulphur Nymph (#16-18): These are deadly before and during hatches, especially near riffles.
• Sulphur Parachute Dun (#16-18): Ideal for surface feeding fish during early morning or late afternoon hatches.
• Midge Larvae (#20-24): These work year-round, but especially well when the water is low and clear.
• Split Case PMD (#18): A subtle emerger pattern that fools picky trout.

Tip: Long leaders and light tippet (6X–7X) are key here. Sight-fishing with nymphs under a dry dropper rig is often productive in slower water. During those larger hatches use streamers to entice larger fish to strike.

3. Northern U.S.: The Au Sable River (Michigan)

The Au Sable is classic northern trout water—gin-clear, spring-fed, and loaded with insects. July brings terrestrial season, which can lead to explosive dry fly takes.

• Foam Beetle (#12-16): Drift along the banks for aggressive strikes.
• Parachute Adams (#14-18): A northern staple that covers mayflies, midges, and general attractors.
• Hopper Patterns (#10-14): Great during windy afternoons or when grasshoppers start jumping into the river. 
• Iso Emergers (#12-14): Isonychia hatches offer great evening dry fly fishing.

Tip: Use stealth when approaching slow runs—these northern trout can be spooky. Late evening dry fly hatches can be magical.

4. West Coast: The Deschutes River (Oregon)

The Deschutes is a rugged Western river known for its redside rainbow trout and fierce caddis hatches in summer. July offers reliable evening action and pocket water opportunities.

• X-Caddis (#14-16): Deadly in the evenings during caddis hatches.
• Elk Hair Caddis (#14-16): A top pick for fast riffles and pocket water.
• PMD Cripple (#16): Effective during mid-morning to afternoon hatches.
• Chubby Chernobyl (#8-12): A great hopper-stonefly hybrid that works as a dry-dropper anchor.

Tip: Wading access can be tough in some areas—use caution. Fish are often tight to structure and in heavy current seams. Don’t overlook swinging soft hackles in the riffles.

Final Thoughts:

Fly fishing in July is all about understanding your local water, adjusting to summer conditions, and staying flexible with your fly box. From tiny midges in the South Holston to foam beetles on the Au Sable, every region has a different rhythm. Keep your flies light, your presentation delicate, and your afternoons shaded—and you’ll find trout willing to play, coast to coast.