Delaware River (Main Stem)
The best month to fish the Delaware River (Main Stem) is May. The month to avoid is August. Right now, in September, it is worth going.
- January: 60 out of 100
- February: 59 out of 100
- March: 55 out of 100
- April: 51 out of 100
- May: 93 out of 100
- June: 71 out of 100
- July: 37 out of 100
- August: 37 out of 100
- September: 71 out of 100
- October: 84 out of 100
- November: 69 out of 100
- December: 64 out of 100
Water averages 65°F this month — fishable, but the margin is thinning. Fish early, land them fast, and stop when the afternoon heats up.
GAUGE 01427510 · COLOURED BY SEPTEMBER
Month by month
| MONTH | TYPICAL FLOW | RANGE (P20–P80) | WATER | AIR HIGH | RAIN | SCORE |
|---|---|---|---|---|---|---|
| January | 3,475 cfs | 2,087–4,679 | 33.2°F | — | — | 60 |
| February | 2,327 cfs | 1,563–3,693 | 33.0°F | — | — | 59 |
| March | 4,279 cfs | 2,858–6,722 | 37.9°F | — | — | 55 |
| April | 5,758 cfs | 2,875–8,616 | 48.0°F | — | — | 51 |
| May | 3,769 cfs | 2,239–5,058 | 58.3°F | — | — | 93 |
| June | 2,123 cfs | 1,400–3,792 | 67.5°F | — | — | 71 |
| July | 1,979 cfs | 1,280–2,799 | 73.5°F | — | — | 37 |
| August | 1,597 cfs | 1,178–3,831 | 69.9°F | — | — | 37 |
| SeptemberNOW | 1,445 cfs | 1,124–2,502 | 64.6°F | — | — | 71 |
| October | 1,934 cfs | 1,469–4,756 | 54.2°F | — | — | 84 |
| November | 2,214 cfs | 1,663–3,353 | 42.2°F | — | — | 69 |
| December | 3,643 cfs | 2,861–4,345 | 35.3°F | — | — | 64 |
WHERE THESE NUMBERS COME FROM
Flow and water temperature are medians of the monthly means reported by USGS gauge 01427510 over 2006-2025. Air temperature and precipitation are ten-year normals from Open-Meteo at this river’s gauge coordinates.
The window is deliberate. USGS’s own full-record statistics for a dammed river reach back before the dam — at Lees Ferry, to 1922, forty-one years before Glen Canyon closed — and describe a river that no longer exists.
Flow is scored against this river’s own fishable band of 1,979–3,643 cfs. There is no universal band: 8,000 cfs is low water on a big tailwater and a flood on a spring creek.
Water temperature is a ceiling rather than a weight. Above about 68°F a trout that is fought and released frequently dies anyway, so no month above that line is scored as worth booking, however good its flow.
The Delaware River (Main Stem) is at its best in May — water around 58°F, flows near 3,769 cfs.
← RIVERS GOING WELL IN SEPTEMBERRegulations, licences and access change without notice and are not reproduced here as fact — check the state agency before you travel. A median describes twenty years; it does not forecast your week. Source: U.S. Geological Survey, National Water Information System.