Susquehanna smallmouth go deep as catfish season peaks in summer heat
Water temperature on the Susquehanna reached 81°F at USGS gauge 01540500 this afternoon — a reading that effectively ends ethical trout fishing for the near term and pushes smallmouth bass into deeper, cooler refuge. Field & Stream's June temperature guide makes clear that the mid-to-upper 60s mark the stress ceiling for trout; at 81°F, the river is firmly in warm-water territory. The good news: catfish are exactly where they want to be. Channel and flathead catfish on PA rivers typically peak through mid-June into August, and this warmth accelerates that timeline. Smallmouth bass, the Susquehanna's calling card, will be most catchable in the early-morning window before surface temps climb — Wired 2 Fish notes that summer bass slide offshore to deep structure once the sun gets high. Flow at 5,220 cfs is within a normal summer range and not a limiting factor. PA Sea Grant has a harmful algal bloom awareness webinar scheduled for June 25, a timely reminder to monitor water quality as temperatures hold elevated.
Current Conditions
- Water temp
- 81°F
- Moon
- Waning Crescent
- Tide / flow
- Susquehanna mainstem flowing at 5,220 cfs per USGS gauge 01540500 — normal summer volume, no flood concern.
- Weather
- Check local forecast before heading out; no current sky or wind data was available.
New to these readings? What do water temp, cfs, tide, and moon phase actually mean for fishing?
What's Biting
Channel Catfish
cut shad on slip-sinker at night in current seams
Smallmouth Bass
topwater at dawn, swing-head jig or crankbait on deep structure by mid-morning
Walleye
tailwater edges at first and last light or after midnight
Trout
avoid warm mainstem — 81°F far exceeds thermal tolerance; check PA regs for any restrictions
What's Next
With water already at 81°F in the second week of June, conditions are tracking toward a warm summer on both the Susquehanna and Allegheny drainages. Unless a significant rain event delivers cooler flows from upstream tributaries, expect temperatures to hold or edge slightly higher through the weekend. Flow at 5,220 cfs at the Susquehanna gauge is within a normal summer range and not a stressor in itself — fish have plenty of river to move in.
For smallmouth bass, the next two to three days are an early-morning game. Bass will push shallow overnight and through dawn, feeding on baitfish and crawfish near rocky riffles and current seams. Once the sun climbs and surface temps spike, they'll retreat to deeper holes, bridge pilings, and any spring-fed tributary mouth they can locate. Wired 2 Fish's summer bass breakdown confirms the pattern: shallow at dawn, deep by mid-morning. A topwater plug — popper or walk-the-dog style — is the play in the first hour of light; after that, transition to a deeper-running crankbait or drop shot to find fish that have pulled off structure. Tactical Bassin also highlights swing-head jigs worked slowly along bottom transitions as a dependable summer approach when bass are holding deep and reluctant to chase.
Catfish anglers have the most favorable window of the week. The combination of warm nights, elevated water temperature, and low light during the waning crescent phase is ideal. Night sessions with cut shad or chicken liver on a slip-sinker rig worked through current seams should produce channel catfish consistently through the weekend. Flatheads, which favor deeper holes with woody cover, are also active — target them with live bluegill or a large sucker fished hard on the bottom near snag-laden structure.
Walleye on the Allegheny are in their difficult mid-summer phase. Heat drives them deep and into a more nocturnal rhythm. The darker nights of the waning crescent favor them somewhat — plan sessions around first light, last light, or after midnight near dam tailwaters for the best odds.
Keep an eye on PA Sea Grant and PA DEP channels for harmful algal bloom advisories. HABs develop rapidly when water exceeds 75°F and flow is moderate; the PA Sea Grant webinar on June 25 is a free resource for learning to identify them before they affect a trip or a pet.
Context
An 81°F Susquehanna reading in the second week of June is on the warmer end of what is typical for this time of year. In most seasons, the mainstem Susquehanna crosses the 75°F threshold in late June and doesn't reach the low 80s until July. Hitting these levels this early suggests the warm season is running ahead of schedule, which can compress the spring transitional bite and push cold-water species into thermal refugia sooner than anglers expect.
No current biologist reports or local tackle shop intel were available in this reporting cycle to benchmark how 2026 is comparing to recent years on these specific rivers. The PA Fish & Boat Commission publishes Biologist Reports by region — those are worth consulting directly before any trip for the most current on-the-water observations from field staff.
Nationally, the warm-water theme is front-of-mind this week. Field & Stream ran a trout temperature guide with a pointed focus on hoot-owl restrictions and fish survival above 68°F. Wired 2 Fish flagged catastrophic fish kills at drought-stressed western reservoirs — conditions far more extreme than PA's current situation, but a useful reminder that thermal thresholds are not abstract: the fish feel them.
For historical context on the Allegheny, that drainage typically stays cooler longer into summer than the lower Susquehanna mainstem, fed by cooler tributaries draining northern Pennsylvania. Walleye and smallmouth fishing on the upper Allegheny corridors generally holds up better into July than comparable mainstem Susquehanna stretches. That regional difference is worth factoring into trip planning as temperatures hold elevated through the coming weeks.
This report is synthesized by Hooked Fisherman from real-time NOAA buoy data, USGS stream gauges, and current reports across regional fishing blogs, captain updates, and angler forums. Source names are cited inline where they appear. Check local regulations before keeping fish. Never trust a single source for a trip decision.