Merced River at Happy Isles Bridge near Yosemite
Merced River · Sierra / West · USGS gage 11264500
Coldwater (summer mean 15.4°C — prime coldwater).
Water
47°F
Flow
10 cfs
Air
54°F
Sky
100%
Pressure
29.95 in
Wind
8 mph
Predicted hatches · 2026-10-31
PredictedBlue-Winged OliveBaetis spp.1.00
Predicted by conditions; no reports yet. water 8.4°C (47°F) sits in the prime band (6-11°C); peak season; 8 days sustained ≥4°C; overcast skies favor it; watch midday, especially overcast afternoons.
flies: BWO Sparkle Dun #18-22, RS2, Pheasant Tail #18
PredictedMidgeChironomidae0.50
Predicted by conditions; no reports yet. water 8.4°C (47°F) sits in the prime band (1-10°C); shoulder of the season; 8 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.