The golden stoneflies might still be active early in the month. Green drakes will be fading waning; carry imitations for the first week of July, just in case you find interested trout. Yellow sallies should be building, and will remain active nearly all month; for some tips and fly patterns, see Beyond the Big Stones.
Pale morning duns are usually morning and early evening hatchers, but on days that are cloudy and cool they will hatch at midday instead.
Pale evening duns are also a July event.
Caddis are active in the evenings. Carry Elk Hair Caddis, X Caddis, and Sparkle Pupas (or similar patterns) in size 14-16. Tan is the most common color; use pupa patterns until evening, then switch to dries as the light starts to fade.
Late in July, attractor patterns such as Royal Wulffs and Turcks Tarantulas are effective during the day, especially when teamed with a size 12-14 Prince or Pheasant Tail on dropper from the hook bend. A popular local attractor pattern is a parachute Madam X variant called the Bar Fly (because everything want to hit on it).
If the weather is very hot, the best fishing times will be 7:30 a.m. to 10:30 a.m., and after 6:00 p.m. In between, you could pick up some trout on nymphs, especially if you tie a 30-inch dropper off a yellow sally imitation and put a Copper John, Prince, Pheasant Tail, or San Juan Worm on the dropper.
That tactic also works in the evening, but shorten the dropper to 18 inches and use a smaller nymph when you're fishing the dusk hours; fish are receptive to that rig on a swing, as well as a dead drift
For more on July tactics and flies, see the Rivers in General forecast