Boise River At Caldwell
Boise River · Rockies · USGS gage 13211205
Trout (marginal) (summer mean 20.4°C — trout, warm in summer).
Water
72°F
Flow
227 cfs
Air
84°F
Sky
0%
Pressure
29.77 in
Wind
5 mph
Predicted hatches · 2026-08-03
PredictedHopper / TerrestrialsAcrididae (grasshoppers)1.00
Predicted by conditions; no reports yet. water 22.2°C (72°F) sits in the prime band (17-24°C); peak season; 8 days sustained ≥14°C; warm sun favors it; watch warm, breezy afternoons.
flies: Morrish Hopper #8-12, Chubby Chernobyl, Dave's Hopper
PredictedTricoTricorythodes spp.0.60
Predicted by conditions; no reports yet. water 22.2°C (72°F) is cooling past the prime band (16-21°C); peak season; 8 days sustained ≥15°C; watch early morning spinner falls.
flies: Trico Spinner #20-24, CDC Trico, Griffith's Gnat
PredictedSlate Drake / IsonychiaIsonychia spp.0.30
water 22.2°C (72°F) is cooling past the prime band (16-21°C); shoulder of the season; 8 days sustained ≥14°C; watch afternoon/evening; nymphs crawl to shore to emerge.
flies: Isonychia #10-12, Slate Drake, Leadwing Coachman
PREDICTED from the first-principles model only. Report-confirmed signal (fly-shop & forum reports) is the next milestone.