Au Sable River
The best month to fish the Au Sable River is October. The month to avoid is September. Right now, in August, this is not the river to book.
- January: 63 out of 100
- February: 62 out of 100
- March: 37 out of 100
- April: 50 out of 100
- May: 64 out of 100
- June: 37 out of 100
- July: 37 out of 100
- August: 37 out of 100
- September: 37 out of 100
- October: 92 out of 100
- November: 74 out of 100
- December: 64 out of 100
Water averages 75°F this month. Above about 68°F a trout that is fought and released often dies anyway, so this is a month to fish somewhere else or at first light only.
GAUGE 04137500 · COLOURED BY AUGUST
Month by month
| MONTH | TYPICAL FLOW | RANGE (P20–P80) | WATER | AIR HIGH | RAIN | SCORE |
|---|---|---|---|---|---|---|
| January | 1,270 cfs | 1,154–1,396 | 33.5°F | — | — | 63 |
| February | 1,173 cfs | 1,103–1,386 | 33.1°F | — | — | 62 |
| March | 1,570 cfs | 1,320–1,749 | 35.2°F | — | — | 37 |
| April | 2,000 cfs | 1,687–2,426 | 43.5°F | — | — | 50 |
| May | 1,545 cfs | 1,446–1,932 | 57.6°F | — | — | 64 |
| June | 1,291 cfs | 1,220–1,524 | 68.9°F | — | — | 37 |
| July | 1,157 cfs | 1,088–1,263 | 75.3°F | — | — | 37 |
| AugustNOW | 1,098 cfs | 1,029–1,219 | 75.1°F | — | — | 37 |
| September | 1,169 cfs | 1,006–1,273 | 69.0°F | — | — | 37 |
| October | 1,212 cfs | 1,085–1,478 | 57.7°F | — | — | 92 |
| November | 1,329 cfs | 1,124–1,520 | 45.1°F | — | — | 74 |
| December | 1,312 cfs | 1,166–1,484 | 35.2°F | — | — | 64 |
WHERE THESE NUMBERS COME FROM
Flow and water temperature are medians of the monthly means reported by USGS gauge 04137500 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 1,173–1,329 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 Au Sable River is at its best in October — water around 58°F, flows near 1,212 cfs.
← RIVERS GOING WELL IN AUGUSTRegulations, 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.