The premier wild trout fishery in the East. Cold tailwater releases from the New York reservoirs sustain wild browns and rainbows on the West Branch, Main Stem, and East Branch. Famous Green Drake hatch and a 6-week Sulphur run.
Hatch timing varies week to week with water temperature and weather. Cross-reference this calendar with West Branch Angler or another local fly shop before planning a trip.
Auto-updated based on the current month. For trips today or this week, this is the section that matters.
Primary winter food
Spring emergence
Big-fish hatch — float guides plan trips around this window
Morning emergence
Bars span the typical emergence window for each hatch on Upper Delaware River. The peak month is outlined and the current month is shaded gold. Mobile users see a month-card view below — a horizontal timeline at 375px is unreadable.
Primary winter food
Spring emergence
Big-fish hatch — float guides plan trips around this window
Morning emergence
Primary winter food
Big-fish hatch — float guides plan trips around this window
Morning emergence
Primary winter food
Morning emergence
Morning spinner falls
Primary winter food
Morning emergence
Morning spinner falls
Primary winter food
Morning spinner falls
Fall emergence
Primary winter food
Fall emergence
Primary winter food
Fall emergence
Primary winter food
Primary winter food
Primary winter food
Primary winter food
Spring emergence
Primary winter food
Spring emergence
Tap a species for the full profile — water temp triggers, fly patterns, and which other rivers run this hatch.
Chironomids · Snowflies
Year-round food source — the only consistent option on tailwaters in winter. On cold sunny days look for noses sipping clusters in slow water.
BWO · Olive · Little Olive
Most reliable Eastern hatch. Two emergences — spring (March-April) and fall (September-October). Best on overcast, drizzly days.
Red Quill · Dark Hendrickson
First substantial mayfly hatch on most Eastern rivers. Spinner falls in evening can be as productive as the dun emergence.
Pale Watery · Little Yellow May
The most important mayfly hatch on Eastern rivers. Reliable emergence + spinner fall every evening for 4-6 weeks. Match the spinners with rusty-bodied patterns.
Eastern Green Drake · Coffin Fly (spinner)
Brief but legendary. The biggest fish in the river will eat these — even fish that never rise to anything else. Penns Creek is the most famous Green Drake river in the East.
PMD
More reliable on tailwaters where stable temps suit the hatch. Often runs concurrently with Sulphurs but emerges in morning rather than evening.
Spotted Sedge · Cinnamon Caddis
Workhorse summer caddis. Heavy emergences and egg-laying flights at dusk through summer. Drop a soft hackle on the swing during the evening.
Cahill
Pale yellow-cream mayfly. Less intense hatch than Sulphur but reliable across many Eastern rivers in late spring through early summer.
Hoppers · Ants · Beetles
Not a hatch but the most important summer trout food in many Eastern systems. Fish tight to grassy banks and overhanging trees. Hopper-dropper rigs are deadly July through September.
Iso · Mahogany Dun (spinner)
Long-running hatch from June into October. Nymphs are strong swimmers and crawl out of the water to emerge — fish a swung wet fly through riffles.
White-Winged Black · Curse
Tiny black-bodied mayfly. The spinner fall — not the dun emergence — is the main event. Look for clouds of spinners over flat water at sunrise.
Calendar entries are flagged "estimated" — regional patterns customized to this river. Always cross-reference with a local fly shop the week of your trip.
Bield: Fish ties USGS gauge data to hatch triggers and alerts you when Upper Delaware Riverhits the temperature window for the hatch you're waiting on. Plan trips around peak emergence, not the calendar.
