Hatch Window

About

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 AT A GLANCE A dashboard shows every saved spot's live conditions in one view, sorted by a plain "fishing well right now" heuristic — fresh, steady flow first. WHAT TO TIE ON A hatch chart matches insect activity to fly patterns by month, water type, and region — covering Western, Northeast, Midwest, and Southern trout water, not just one corner of the country. YOUR CATCH LOG Log the date, spot, flies, conditions, and notes for every outing. It stays on your device, survives app updates, and builds a "what worked here before" view for each spot — plus a one-tap shareable outing report. PRIVACY No account, no login, no ads, no tracking. Hatch Window talks to exactly two free public data services — USGS Water Services for stream conditions and Open-Meteo for weather — and nothing else. Your catch log and spot list never leave your device. Full privacy policy is in the app. Hatch Window is a v1 built by one angler who wanted these five things in one place instead of five different tabs. More coverage and features are on the way.