Jefferson River Near Twin Bridges
Jefferson River · Rockies · USGS gage 06026500
Trout (marginal) (summer mean 19.6°C — trout, warm in summer).
Water
56°F
Flow
491 cfs
Air
48°F
Sky
0%
Pressure
30.10 in
Wind
8 mph
Predicted hatches · 2026-09-15
PredictedSpotted / Summer CaddisHydropsyche spp.0.35
Predicted by conditions; no reports yet. water 13.4°C (56°F) is warming toward the prime band (14-19°C); shoulder of the season; 7 days sustained ≥12°C; watch evening, last hour of light.
flies: Elk Hair Caddis #14-16, Iris Caddis, X-Caddis
PredictedMidgeChironomidae0.22
water 13.4°C (56°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.