Free Resource · Updated 2026
The complete fly hatch chart for Pennsylvania's legendary limestone streams and freestone rivers. From the revered Penn's Creek Green Drake hatch to the Brodhead, Loyalsock, Kettle Creek, and Yellow Breeches tailwater — select your stream below for peak hatch timing, fly pattern recommendations, and current month highlights for 2026.
Pennsylvania Hatch Calendar — Quick Reference
Pennsylvania Streams
Penn's Creek · Spring Creek · Little Lehigh
Stable year-round water temps driven by groundwater mean hatches arrive 1–2 weeks earlier in spring and persist longer into fall than freestone streams. The Green Drake and Sulphur hatches peak on limestone creeks before they fire on the freestone rivers. Consistent flows create predictable evening hatch windows and dense, reliable activity.
Brodhead · Loyalsock · Kettle Creek · Pine Creek · Pohopoco
Snowmelt and rain-driven flows mean hatch timing tracks air temps closely. Expect hatches to run 1–2 weeks behind limestone creeks in spring. High water years push Green Drake timing later into June. Flows need to drop and clear after rain events before hatches fire consistently.
Yellow Breeches · Tulpehocken
Cold, regulated releases from reservoirs extend the season at both ends — midges fish through winter, and BWOs stay active into late November. Summer hatches can be muted when dam releases keep temps artificially cold. Best hatch windows typically occur when generation is low and surface temps can rise slightly through the day.
The Why Behind the Chart
Ephemerella subvaria
The first major mayfly of the Pennsylvania season and a signal that dry fly fishing has arrived. Hendricksons emerge in the afternoon when water temps climb into the mid-40s°F, typically between 2–5pm on sunny April days. Trout that have been deep and lethargic all winter come up aggressively to feed — often the first surface-feeding you'll see all year. Fish the dun as it drifts in the film; a trailing Pheasant Tail nymph is deadly just before the hatch fires.
Recommended: #12–14 Hendrickson Comparadun, A.P. Nymph
Ephemera guttulata
Penn's Creek's legendary hatch and arguably the most anticipated event in eastern fly fishing. Water temps hitting 55–62°F trigger the hatch, which fires at dusk between 7–9pm. Large, creamy mayflies blanket the surface and big brown trout that rarely show themselves commit fully to feeding. Fish the dun through the evening, then switch to a Coffin Fly spinner as dark falls. Access points from Coburn downstream to Poe Paddy State Park are prime. Expect crowds — this hatch draws anglers from across the country.
Recommended: #8–10 Green Drake Comparadun, Coffin Fly spinner
Ephemerella dorothea
Pennsylvania's most reliable and longest-running evening hatch. Sulphurs begin in May on limestone creeks and run through July, providing consistent dry fly action for nearly three months. The hatch fires around 7pm and intensifies at dusk — look for trout sipping in the tail-outs and slow glides. On limestone streams like Penn's Creek and Spring Creek, the hatch is dense enough that trout become selective and a well-presented #16–18 imitation matters.
Recommended: #16–18 Sulphur Sparkle Dun, Parachute Adams
Tricorythodes sp.
A summer morning ritual on Pennsylvania's limestone and tailwater streams. Trico spinner falls happen at first light — often over by 9am — and require the most technical presentation of any PA hatch. Trout sip tiny spent spinners in flat, clear water. Use 6X or 7X tippet, approach low and slow, and target individual risers. The Yellow Breeches and Penn's Creek offer excellent Trico fishing from July through September.
Recommended: #22–26 Trico Spinner, CDC Trico
Ephoron leukon
A late summer spectacle unique to a handful of PA rivers. White Flies emerge in massive numbers at dusk on Penn's Creek and Yellow Breeches — the air can appear to snow with them on peak evenings in mid-August. Trout feed in a frenzy and the window is short, intense, and unforgettable. Bring a headlamp; the best fishing often extends after dark. The hatch is so thick that attractor patterns can outfish exact imitations.
Recommended: #14 White Wulff, White Parachute
Baetis sp.
PA's most versatile hatch — present on every stream type, spring and fall, and most reliable on overcast, drizzly days when other hatches won't cooperate. BWOs emerge in two seasonal windows: late March through May and again September through November. On tailwaters like Yellow Breeches and Tulpehocken, they fish well even in winter. When the weather looks bad, think BWO — trout know the hatch and so should you.
Recommended: #18–22 Sparkle Dun, RS2 emerger
Pennsylvania is the birthplace of American fly fishing and its hatch calendar reflects that rich heritage. The season begins with Hendrickson hatches in April on Penn's Creek and the Brodhead — the first major mayfly hatch of spring. March Browns follow in May, and Blue-Winged Olives fish well throughout spring and fall on all PA streams.
The Green Drake hatch on Penn's Creek (Ephemera guttulata) is considered one of the greatest hatch events in the eastern United States — drawing anglers from across the country for the brief but spectacular window in late May and early June. Large, creamy mayflies blanket the water at dusk, triggering explosive feeding from the stream's wild brown trout. The Green Drake also hatches on the Brodhead, Loyalsock, and Kettle Creek during the same period.
Sulphur hatches run from May through July on most PA streams — long, reliable evening hatches that provide consistent dry fly action. August brings Trico spinner falls and the distinctive White Fly hatch. Fall Autumn Caddis and BWOs extend the season through November. Use FlyFishFinder's flow alerts to know when your target stream is fishing at its best.
See Live Pennsylvania River Conditions →Common Questions
Late May through early June, typically peaking around Memorial Day weekend. The hatch fires at dusk when water temps reach 55–62°F. Exact timing shifts by a week depending on spring warmth — limestone spring creeks like Penn's Creek tend to run slightly earlier than freestone streams.
May is Pennsylvania's richest month for hatches. Carry March Browns (#10–12), Green Drake Comparaduns (#8–10), and Sulphur Sparkle Duns (#16–18). A Coffin Fly spinner for evening Green Drake falls on Penn's Creek is essential late in the month. A Pheasant Tail nymph covers you between hatches.
Sulphurs are an evening hatch, typically firing around 7pm and intensifying at dusk, from May through July. Limestone streams like Penn's Creek and Spring Creek tend to have the most consistent and dense Sulphur hatches in PA.
Limestone spring creeks (Penn's Creek, Spring Creek, Little Lehigh) run 1–2 weeks earlier in spring due to stable groundwater temps. Freestone streams (Loyalsock, Kettle Creek, Pine Creek) track air temps more closely, so hatches arrive later and can be disrupted by high water after rain events.
Yellow Breeches is a tailwater with year-round fishing opportunities. Midges (#22–26) work through winter. Sulphurs and Tricos are summer staples. BWOs fish well spring and fall, especially on overcast days. The White Fly hatch in August is a late summer highlight.
May is the peak month — Green Drakes, March Browns, and Sulphurs overlap for a remarkable few weeks. April brings the first Hendricksons on limestone creeks. Fall (September–October) offers excellent BWO and Autumn Caddis fishing with fewer crowds and beautiful scenery.
FlyFishFinder combines hatch knowledge with live gauge alerts, Prime condition indicators, and real angler intel — so you show up on the right day, not the wrong one.
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