Roaring Fork River above Difficult Creek near Aspen, Co.
Roaring Fork River · Rockies · USGS gage 09073300
Coldwater (summer mean 12.3°C — prime coldwater).
Water
52°F
Flow
30 cfs
Air
55°F
Sky
84%
Pressure
29.89 in
Wind
5 mph
Predicted hatches · 2026-09-15
PredictedBlue-Winged OliveBaetis spp.0.57
Predicted by conditions; no reports yet. water 11.0°C (52°F) sits in the prime band (6-11°C); shoulder of the season; 7 days sustained ≥4°C; overcast skies favor it; watch midday, especially overcast afternoons.
flies: BWO Sparkle Dun #18-22, RS2, Pheasant Tail #18
PredictedMidgeChironomidae0.42
Predicted by conditions; no reports yet. water 11.0°C (52°F) is cooling past the prime band (1-10°C); shoulder of the season; 7 days sustained ≥0°C; watch midday, especially cold months.
flies: Zebra Midge #18-22, Griffith's Gnat, Disco Midge
PREDICTED from the first-principles model only. Report-confirmed signal (fly-shop & forum reports) is the next milestone.