Fly fishing hatch timing
Hatch calendars for the
top 50 Eastern US trout rivers.
Month-by-month timing for every major hatch — Sulphurs, Green Drakes, Hendricksons, BWOs, October Caddis, Trico spinner falls — across 13 states from Maine to Georgia. Each calendar lists peak windows, fly patterns, water temperature triggers, and time of day so you can plan the right trip on the right week.
A note on hatch timing
Hatches respond to water temperature, not the calendar. These windows are regional norms — always cross-reference with a local fly shop the week of your trip. Bield: Fish ties USGS gauge readings to hatch triggers in the app.
What's hatching now — May
Pennsylvania
Penns Creek
- · Midge (heavy)
- · Blue Winged Olive (heavy)
Pennsylvania
Big Fishing Creek
- · Hendrickson (heavy)
- · Sulphur (heavy)
Pennsylvania
Brodhead Creek
- · Hendrickson (heavy)
- · Sulphur (heavy)
Pennsylvania
Little Juniata River
- · Midge (heavy)
- · Blue Winged Olive (heavy)
New York
West Branch Delaware River
- · Midge (heavy)
- · Blue Winged Olive (heavy)
Pennsylvania
Upper Delaware River
- · Midge (heavy)
- · Blue Winged Olive (heavy)
New York
Beaverkill River
- · Quill Gordon (heavy)
- · Hendrickson (heavy)
Pennsylvania
Loyalsock Creek
- · Hendrickson (heavy)
- · Sulphur (heavy)