Free Resource · Updated 2026
The Clark Fork is a large freestone river that flows west through Missoula and across the Idaho border. It is the longest river in Montana and offers diverse fishing from the upper river near Deer Lodge to the canyon sections below Missoula. The Skwala hatch is exceptional here and summer fishing with PMDs and hoppers is reliable.
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Clark Fork River Hatch Calendar at a Glance
The Clark Fork near Missoula is the most accessible stretch and gets the most fishing pressure. The river upstream toward Deer Lodge is less crowded and holds good fish in the riffles and runs. Below Missoula, the river enters canyon sections best accessed by boat.
The Skwala hatch on the Clark Fork is one of the best in the state. It starts in late February and peaks in March, with large stoneflies crawling on rocks and bankside vegetation. Fish a size 8 Skwala Adult or Chubby Chernobyl during the warmest afternoon hours.
Summer fishing with PMDs and hoppers runs from June through September. The river sees less pressure than the Madison or Yellowstone despite being large and productive. Fall fishing with October Caddis in September and October rounds out the season.
See the full Montana Fly Hatch Chart for hatch timing across all of Montana's top trout streams.
Check Conditions Near Clark Fork RiverWhat to Fish
The Skwala hatch is the Clark Fork's signature early-season event. It fires on warm afternoons starting in late February and runs through April. Fish the slower water near the banks and look for fish rising in the softer currents. The hatch is best where stonefly shucks are visible on streamside rocks.
Recommended: #8 Skwala Adult, Chubby Chernobyl
The Salmonfly hatch moves through the Clark Fork system in late May. Float trips during the hatch window give access to water that cannot be reached from the banks. Look for adults in streamside willows and fish downstream of concentrations.
Recommended: #4-6 Stimulator, Chernobyl Ant
PMDs are consistent throughout summer on the Clark Fork. Morning hatches produce reliable rises in the flatter sections. The river is wide so longer leaders and careful approaches pay off during PMD hatches.
Recommended: #16-18 Sparkle Dun, CDC Dun
The October Caddis hatch is a fall highlight on the Clark Fork. Large orange caddis adults bring big trout to the surface in September and October. Fish the slower tailouts in the evening when adults are most active. A size 8 Orange Stimulator is the classic pattern.
Recommended: #8 Orange Stimulator, October Caddis Adult
Live readings from USGS gages on the river.
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