▲ Fly Fish ForecastBeta

Hatch predictions for 300+ US rivers — built from live water & weather, then confirmed against real fly-shop reports.

← All rivers

South Fork Bull Run River Near Bull Run

South Fork Bull Run River · Pacific NW · USGS gage 14139800

Coldwater (summer mean 13.4°C — prime coldwater).

Water
47°F
Flow
36 cfs
Air
44°F
Sky
46%
Pressure
29.91 in
Wind
6 mph
Predicted hatches · 2026-10-30
PredictedBlue-Winged OliveBaetis spp.1.00
Predicted by conditions; no reports yet. water 8.2°C (47°F) sits in the prime band (6-11°C); peak season; 8 days sustained ≥4°C; watch midday, especially overcast afternoons.
flies: BWO Sparkle Dun #18-22, RS2, Pheasant Tail #18
PredictedMidgeChironomidae0.50
Predicted by conditions; no reports yet. water 8.2°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.