Hatch Window

Hatch Window is a fly-fishing companion for deciding where to go, when to go, and what to tie on — built to run entirely on your phone. WHERE TO GO A curated starter list of well-known trout waters, plus any spots you add yourself. Everything is saved on-device. CONDITIONS, NOT GUESSES Live streamflow (cfs) and gauge height for each spot, pulled from the USGS Water Services API. If a gauge has no data, is offline, or the network fails, Hatch Window says so — it never shows a made-up number. BEST TIMES TO FISH Sunrise, sunset, civil twilight, and solunar major/minor feeding windows, computed on your device from standard astronomical formulas. Solunar theory is a traditional angling heuristic, and the app says so — no overclaiming. PLAN AHEAD A 7-day outlook per spot ranks the coming days by their best solunar window, so you can pick your day instead of only checking today. ALL YOUR SPOTS…