Yellowstone River Fishing in April

Fly Fishing the Yellowstone River in April

As valley floor snowpack melts in March and early April, Yellowstone River trout begin to awaken. The lower stretches of Paradise Valley come to life as fish begin to migrate, feed, and move throughout the system.

The mouths of Nelson’s and Depuy’s Spring Creeks teem with rainbow and cutthroat trout preparing to spawn.

Early spring fishing conditions on the Yellowstone River are best described as unpredictable. As the longest undammed, free flowing river in the Lower 48 States, water levels on the Yellowstone River fluctuate rapidly. Snow and rain can spike flows and muddy up water clarity.

Cool, consistent temperatures throughout April, however, will keep the river in great shape right up until the start of the runoff, which usually starts sometime in early May.

Yellowstone River Fly Fishing Hatches in April

Blue-winged olive mayflies (BWOs) and midges are active in April. March browns and caddis emerge later in the month as spring finally arrives in Montana. The Mother's Day caddis hatch generally begins in late April or early May.

Fishing the Mother’s Day Caddis Hatch on the Yellowstone River

The Yellowstone River experiences a caddis hatch near Mother's Day, that’s widely considered one of the best caddis hatches in the western U.S. Unimaginable rafts of bugs cover the river's surface, which can make for fishing fantastic.

But, it’s not that simple.

Typically, the Mother's Day hatch starts in late April as the weather warms up and daytime temperatures reach the high 70s or even low 80s. Warmer air means warmer water, which triggers the caddis to hatch. But that same increase in temperature also begins to melt higher elevation snow-pack, increasing flows and decreasing water clarity.

If you manage to hit that Goldilocks window, when the insects are hatching but the runoff has not yet come down, you might experience some of the greatest dry fly fishing of your life.

Based on our 23+ years of guiding Yellowstone River fishing trips, the best-case scenario goes like this: The weather gradually warms up, reaching into the 70s or 80s for a few days and causing the caddis to start emerging. Then, a cooler weather front pushes through, slowing the hatch but keeping the river clear for another week or two following the initial emergence. When the hot weather inevitably returns, the hatch will explode, and the fishing will be amazing for a few days before runoff reaches the Paradise Valley stretches.

In this best-case scenario, anglers can expect good fishing once the caddis arrive, with some days being exceptional, both on dries and dry/dropper rigs for these two weeks. That said, some years runoff all but stifles this famed hatch event.

Yellowstone River Fly Fishing Techniques in April

As with most regional waters in Southwest Montana, early season fishing generally relies on dead drift nymphing and stripping streamers. Expect to employ varied techniques, adjusting your approach to capitalize on changing conditions.

Standard nymph setups include tandem rigs with added split shot, fished about 6 feet under a strike indicator. Switch to dries when you encounter actively rising fish, looking for heads on the insides of gentle seams and in back eddies.

Articulated streamers—in light colors—fished near undercut banks and along gravel-bar drop-offs elicit more and more strikes as the weather warms.

Bozeman Fly Fishing Guide Pro-Tip:

Fly fishing Montana's famed Yellowstone River during April can be epic. Fish are eager to feed as the temperatures warm, providing great angling opportunities using nymphs, streamers, and dry flies. Look for foam eddies between Emigrant, MT, and Loch Leven Fishing Access Site, and high-stick, BWO nymphs below an indicator.

Our Yellowstone River Fly Box for April