Yellowstone River Montana Hatch Chart - Paradise Valley

South-central Montana, from Gardiner to Livingston. The Yellowstone River exits Yellowstone National Park at Gardiner and immediately enters one of the most celebrated stretches of trout water in the American West - the Paradise Valley. For roughly 50 miles the river runs north through a wide mountain valley flanked by the Absaroka Range to the east and the Gallatin Range to the west, before reaching Livingston and the transition to the broader prairie valley below.

This is big freestone water - powerful, fast, and wade-able in places with care. Wild rainbow and brown trout throughout, with cutthroat more common in the upper reach near Gardiner. Fish average 14-18 inches with trophy fish - particularly large browns - present especially in the lower valley near Livingston. The Yellowstone is one of the longest free-flowing rivers in the lower 48, and the Paradise Valley section retains its wild, undammed character.

Check current Montana FWP regulations before you go. The Yellowstone has specific seasonal rules, gear restrictions, and emergency closures - particularly during warm summer periods when fish can be stressed by high water temperatures. If river temperatures exceed 73°F, consider fishing early morning only or postponing your trip.

Shop by type: dry flies, nymphs, Euro nymphs, hoppers and terrestrials, streamers.

Year at a glance

Month Primary hatches Also carry Typical sizes
Jan Midges BWO on mild days, stonefly nymphs 18-22
Feb Midges, BWO Small dark stonefly nymphs 16-22
Mar BWO, midges Skwala on lower valley, streamers 16-22, Skwala 8-12
Apr BWO, Skwala, March Brown Early caddis, streamers 12-18
May Caddis, BWO Stonefly nymphs, runoff mid-month Caddis 14-16, BWO 16-20
Jun Salmonfly, golden stone, caddis PMD late month Stones 4-10, caddis 14-16
Jul PMD, caddis, yellow sally Hoppers start, tricos on flat sections 14-18
Aug Hoppers, caddis, tricos Ants, beetles, late PMD - monitor temps Hopper 8-12, trico 20-22
Sep Hoppers, BWO, mahogany dun Streamers for pre-spawn browns 10-18, BWO 18-20
Oct BWO, mahogany dun, October caddis Midges, streamers BWO 18-22, caddis 8-12
Nov BWO, midges Streamers for post-spawn browns 18-22
Dec Midges Small nymphs, streamers 18-22

January

The Yellowstone fishes year-round through the valley. January midge activity can be excellent on calm, mild afternoons. Fish concentrate in slower, deeper water - the inside bends and tailouts below riffles. The upper reach near Gardiner tends to fish better in winter due to geothermal influence from the park drainage.

February

Same midge program with increasing BWO activity on overcast afternoons. The lower valley near Livingston can fish well on calm winter days. Midday is the window.

March

BWO pick up as days lengthen. Skwala stoneflies begin on the lower valley water when temperatures warm - the Yellowstone is one of the better Skwala rivers in Montana. Streamer fishing for pre-runoff browns can be strong through the entire valley in March.

April

Olives, March Browns, and Skwala provide good dry-fly opportunities on gray days. Caddis begin late in the month. Runoff typically starts building toward the end of April - fish the first half of the month before flows push.

  • BWO and March Brown, 12-18, on cloudy afternoons.
  • Skwala on warm bank water in the lower valley.
  • Early dark caddis at dusk.
  • Streamers in off-color water as flows begin to rise.

May

Caddis hatches can be excellent in early May before runoff peaks. The Yellowstone typically blows out mid-month - often running high and dirty through early June depending on snowpack in the Absarokas. Fish the edges, side channels, and any clear water near tributary mouths when the main river is pushing.

June

The salmonfly hatch is the defining event of the Yellowstone's year. As flows drop and clear - usually mid-to-late June - the hatch moves upstream from the lower valley toward Gardiner. The timing varies significantly year to year depending on snowpack and temperatures. Golden stones follow and extend the big-bug fishing into early July. Book guides and lodges well in advance for the salmonfly window - this is the most sought-after hatch in Montana.

  • Salmonfly - 4-8. A West Fork Salmonfly hard against undercut banks, root wads, and cliff faces. Fish the leading edge upstream of where adults are thickest.
  • Golden stone - 6-10. Overlaps and follows the salmonfly. Stone nymph dropper 18 inches below a dry.
  • Evening caddis - 14-16. Elk hair.
  • Late June: PMD begins in riffles, 16-18. Pale Morning Dun.

July

Outstanding summer dry-fly fishing. PMDs in the morning, caddis in the evening, hoppers starting along the valley grass and sage. The river sees significant float traffic in July - wade-anglers should target early morning or evening and focus on sections away from the main launch sites. Monitor water temperatures in late July - if temps approach 70°F, fish early and release quickly.

August

Hopper season on one of the best hopper rivers in Montana. The wide valley, long grass banks, and big brown trout make August a destination month - but monitor water temperatures carefully. The Yellowstone can warm significantly in August during hot, dry years and Montana FWP occasionally issues hoot owl restrictions (no fishing after 2 PM). Check current conditions before each trip. Fish early, fish efficiently, and release quickly.

  • Hoppers - 8-12. A hopper-dropper with a small nymph underneath. Shop hoppers and terrestrials.
  • Trico - 20-22. Early morning spinner falls on flat water near Livingston.
  • Ants and beetles in foam lines along grassy banks.
  • Late PMD on cool mornings.
  • Evening caddis.

September

One of the great months on the Yellowstone. Hoppers hold through mid-September. Mahogany duns and olives arrive in the afternoon. Brown trout begin staging ahead of the spawn - the largest fish of the year move into shallower feeding lanes and respond aggressively to dries and streamers. Crowds drop sharply after Labor Day. Water temperatures cool and fishing quality improves significantly.

  • Hoppers and ants through mid-September.
  • Mahogany dun - 14-16 on gray afternoons.
  • BWO - parachute BWO and Baetis emerger, 18-20.
  • Streamers at first and last light for staging browns.

October

Fall colors in the valley and aggressive pre-spawn brown trout. October caddis in the afternoons, olives and mahogany duns on cloudy days. Streamer fishing through the deeper slots and undercut banks can produce the largest fish of the year. Handle spawning fish carefully - avoid fishing to fish actively on redds.

  • October caddis - 8-12, large orange dry.
  • Mahogany dun and BWO on overcast days.
  • Midges in slow water and tailouts.
  • Streamers - olive, black, and brown through deeper holding water.

November

Spawning winds down. Cold mornings, short days. BWO and midges in the warmest part of the afternoon. Post-spawn browns hold in deeper runs and respond to streamers swung slowly through slower water.

  • BWO and midges, 18-22.
  • Streamers in deeper, slower runs.
  • Small nymphs through holding lies.

December

Midge and nymph program. Low, clear water and cold mornings. The upper reach near Gardiner can fish surprisingly well in December on mild days due to the geothermal influence from the park.

A western dry and nymph assortment covers the year. Add a salmonfly pattern, hoppers, trico patterns, mahogany duns, and a full streamer box for the complete Paradise Valley experience.