July Fishing on the Yellowstone River

July weather, stream flows, and summary

July is the Yellowstone River’s showcase month. The month kicks-off with the salmonfly hatch, followed-up by numerous other strong hatches, and as the month fades grasshoppers begin to show. July is the reward for waiting out the Yellowstone River’s nearly eight weeks of snowmelt runoff. With pleasant weather, consistently dropping stream flows, and diverse hatches, July on the Yellowstone River is often a safe bet for some of the best fishing of the year. 

Angling days in July are long, averaging just over 15 hours of daylight a day. The average daily high temperature of 85 degrees F reflects the long days of sunshine. Only 1.5” of accumulated precipitation falls in July, making it one of the driest months of the year. With these long, warm days fishing the Yellowstone River can be good throughout the day, including early morning and late evening. 

In most years, snowmelt runoff is complete by the first week of July and stream flows drop and clear more and more each day. If June receives above average precipitation or is colder than average, snowmelt runoff on the Yellowstone River may continue through the first week of July. If these two weather patterns occur, the river doesn’t become fishable until after July 5th. 

As the longest undammed river in the lower 48, the Yellowstone River boasts nearly 150 miles of trout-friendly water. From Gardiner and the Yellowstone National Park boundary downstream to just east of Columbus, the Yellowstone River flows through varied topography—feeling at times like a mountain freestone with large rapids and pocket water to a meandering prairie river with long riffles and runs framed with banks of tall cottonwoods. Throughout these 150 miles the river has various sections with distinctly unique characteristics. It feels like several rivers all in one. 

The Yellowstone River is also home to native Yellowstone cutthroat trout. This trout is one of two subspecies of native cutthroat trout in Montana. The Yellowstone Cutthroat trout is native only to waters draining into the Yellowstone River. The river upstream of Emigrant boast the majority of the Yellowstone cutthroat trout, with populations increasing closer to Gardiner and Yellowstone National Park. 

The Yellowstone River in July features many things that make summer-time fly fishing in Montana so desirable. Back dropped by the Gallatin, Absaroka, Crazy, and Beartooth mountain ranges, the Yellowstone River experiences strong hatches throughout July. Pair these hatches with pleasant weather and a river coming out of snowmelt runoff and July is the gold-standard on the Yellowstone. 

July fishing: what to expect

The Yellowstone River in July is a case-study in the best attributes of Montana fly fishing. There are opportunities for catching fish using a variety of methods. From drifting big dry flies along the banks to dragging streamers through deep runs or dead-drifting two-fly weighted nymph rigs, something exists for all anglers to enjoy a river coming into its prime. 

A typical day in early July might look different than a typical day later in the month. In early July as salmonflies and Golden stroneflies are hatching, fishing big dry flies in sizes 6 through 10 along the banks may be the best way to catch fish. The river upstream of Livingston gains most of the focus early in July as the majority of salmon- and Golden stoneflies inhabit the river in this section. Miles of willow-lined banks provide ideal habitat for hatching stoneflies. 

As the second week of July comes and flows continue to drop, hatches of caddis and PMDs increase in frequency. The large riffle and run sections of the Yellowstone River downstream of Livingston become more angler friendly as flows drop. The riffle-run type of water that is prevalent downstream of Livingston fishes better as flows drop below 7,000 cfs. 

Because the days are long, an understanding of choosing the best time to fish is important. The lowlight hours of early morning and evening are often best for targeting large fish with streamers or dry flies. Later in the month when grasshoppers begin to show up in streamside grasses, midday and late afternoon are ideal for prospecting with a terrestrial. 

Dry fly anglers can find surface action even in the bright sun of midday and afternoon on the Yellowstone River. During July, PMD, caddis, and stonefly nymphs are usually active throughout the day, so anglers looking to fish subsurface should use a two-fly nymph rig with a stonefly nymph size 8 to 12 and a smaller caddis or PMD nymph size 12 to 16. 

Where to find July trout on the Yellowstone

Finding trout on the Yellowstone River in July is a matter of fishing the appropriate hatch. Early in July-especially when the river is still running high—stoneflies dominate the hatch chart. Because most stoneflies hatch from bankside structure and streamflows are fast and high in early July, most trout will be found near the bank. 

As streamflows lower, trout will follow the hatches. Because the Yellowstone River is one of the largest trout rivers in Montana and has high and fast streamflows the first two weeks of July, bankside structure riffle corners, and slower water in back eddies will hold most trout. By late July hatches of PMDs and caddis provide the bulk of a trout’s diet. These hatches paired with streamflows being lower than earlier in the month, cause Yellowstone River trout migrate away from the banks and move from various feeding and holding lies in riffle corners, shelfs, drop-offs, and pockets. 

Because the Yellowstone River has an abundance of aquatic insect life, trout inhabit many places, but are most often found along the bank, in riffles, shelfs, the heads of runs, and the tail outs of runs. These habitats all offer the primary needs for trout: available food source, cover from predators, cover from strong currents, and flowing water for oxygen. During July on the Yellowstone River the trout tend to be hungry and happy and in the right spots.

Important July hatches

Stoneflies are abundant early in July on the Yellowstone River. Salmonflies kick-off the month hatching around Livingston, proceeding upstream to the river near Gardiner and just outside of Yellowstone National Park. Shortly after the salmonfly hatch, and sometimes simultaneously, Golden stoneflies and Yellow Sally stoneflies hatch. 

Most stoneflies hatch in the first two weeks of July, followed by hatches of caddis and Pale Morning Dun (PMD) mayflies. A variety of caddis species ranging in size from 10 to 20 live in the Yellowstone River and hatch throughout the month, occurring at various times of the day. 

PMD hatches typically begin mid-morning and last for several hours. Insects range in sizes from 12 to 18, with most being size 16. As a mayfly, it is important to understand trout may feed on emerging PMDs and not exclusively on fully hatched adults. 

Grasshoppers, although not an aquatic insect, can be found on bankside grasses in late July. Opportunistic trout will eat a grasshopper that has mistakenly found its way onto the water. 

Yellowstone River fly box for July

Stonefly nymphs in brown and black in sizes 4 to 10

Golden stonefly dry flies in sizes 8 and 10

Salmonfly dries in size 4 to 8

Yellow Sally nymphs in sizes 10 to 16

Yellow Sally dry flies in sizes 10 to 16

PMD nymphs sizes 12 to 18

PMD emergers sizes 12 to 18

PMD dry flies sizes 12 to 16

Caddis pupae sizes 12 to 16

Caddis CDC emergers sizes 12 to 16

Caddis dry flies with dark grey, black or brown bodies in sizes 12 to 18; 

Grasshoppers in sizes 4 to 12

Ants and beetles in sizes 12 to 18

Crayfish patterns in sizes 2 to 8

Sculpin patterns in sizes 2 to 6

Streamers in olive, black or brown in sizes 2 to 6