La Crosse River @ Cnty Trunk Highwy Bb near Tomah,Wi
La Crosse River @ Cnty Trunk Highwy Bb · Driftless / Midwest · USGS gage 05382267
Trout (marginal) (summer mean 17.3°C — trout, warm in summer).
Water
62°F
Flow
81 cfs
Air
69°F
Sky
4%
Predicted hatches · 2026-06-16
PredictedGolden StoneHesperoperla / Calineuria1.00
Predicted by conditions; no reports yet. water 16.7°C (62°F) sits in the prime band (14-18°C); peak season; 8 days sustained ≥13°C; watch afternoon and evening.
flies: Chubby Chernobyl #8-10, Yellow Stimulator, Pat's Rubber Legs
PredictedSulphurEphemerella dorothea / invaria1.00
Predicted by conditions; no reports yet. water 16.7°C (62°F) sits in the prime band (15-19°C); peak season; 8 days sustained ≥13°C; watch evening, the last two hours of light.
flies: Sulphur Comparadun #16-18, Sulphur Spinner, Pheasant Tail
PredictedEastern Green DrakeEphemera guttulata1.00
Predicted by conditions; no reports yet. water 16.7°C (62°F) sits in the prime band (14-18°C); peak season; 8 days sustained ≥12°C; watch evening; the spinner (Coffin Fly) falls at dusk.
flies: Green Drake #8-10, Coffin Fly Spinner, Drake Emerger
PredictedSalmonflyPteronarcys californica0.65
Predicted by conditions; no reports yet. water 16.7°C (62°F) is cooling past the prime band (13-16°C); peak season; 8 days sustained ≥12°C; watch late morning through evening.
flies: Rogue Foam Salmonfly #4-6, Chubby Chernobyl, Pat's Rubber Legs
PredictedLight CahillStenacron / Stenonema0.60
Predicted by conditions; no reports yet. water 16.7°C (62°F) sits in the prime band (16-20°C); peak season; watch dusk.
flies: Light Cahill #14-16, Cream Cahill, Cahill Spinner
PredictedPale Morning DunEphemerella spp.0.50
Predicted by conditions; no reports yet. water 16.7°C (62°F) sits in the prime band (13-18°C); shoulder of the season; 8 days sustained ≥12°C; watch late morning to early afternoon.
flies: PMD Comparadun #16-18, Sparkle Dun, Pheasant Tail #16
PredictedSpotted / Summer CaddisHydropsyche spp.0.50
Predicted by conditions; no reports yet. water 16.7°C (62°F) sits in the prime band (14-19°C); shoulder of the season; 8 days sustained ≥12°C; watch evening, last hour of light.
flies: Elk Hair Caddis #14-16, Iris Caddis, X-Caddis
PredictedMarch Brown (Eastern)Maccaffertium vicarium0.50
Predicted by conditions; no reports yet. water 16.7°C (62°F) sits in the prime band (14-18°C); shoulder of the season; 8 days sustained ≥12°C; watch sporadic through the day, midday into afternoon.
flies: March Brown #10-12, Hare's Ear, Spinner
PredictedSlate Drake / IsonychiaIsonychia spp.0.50
Predicted by conditions; no reports yet. water 16.7°C (62°F) sits in 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
PredictedGreen DrakeDrunella spp.0.43
Predicted by conditions; no reports yet. water 16.7°C (62°F) is cooling past the prime band (11-15°C); peak season; 8 days sustained ≥10°C; watch midday, often cloudy.
flies: Green Drake Parachute #10-12, Cripple, Hares Ear #10
PREDICTED from the first-principles model only. Report-confirmed signal (fly-shop & forum reports) is the next milestone.