About Perigee
Perigee is a coastal data platform: live tide charts, high and low tide predictions, water levels, currents, marine weather, and the sun and moon — for every NOAA station on the US coast, and for the AI agents that increasingly answer questions about them.
Where the data comes from
Every tide number on Perigee originates with NOAA CO-OPS — the Center for Operational Oceanographic Products and Services, the federal authority that operates the national water level observation network. Predictions are NOAA's harmonic predictions (datum MLLW), observations are the six-minute gauge readings, and station metadata, datums, and flood thresholds come from NOAA's metadata service. Wind and marine forecasts come from the National Weather Service. Sun and moon times are computed locally with well-established astronomical algorithms. We transform, chart, and interpret; we do not alter the underlying measurements.
How the site works
Station pages refresh their tide tables daily and their live readings every six minutes. Annual tide tables, king tide calendars, and minus tide calendars are computed from full-year NOAA predictions. When NOAA is briefly unreachable we say so rather than showing stale numbers as fresh.
Who runs it
Perigee is built and maintained by Cardin Labs, an independent software studio. Questions, corrections, and partnership ideas: ryandcardin@gmail.com.
For developers and AI agents
Everything on the site is available programmatically: a free REST API and a hosted MCP server (https://perigeetides.com/mcp) that lets AI assistants like Claude query tides, currents, water levels, and astronomy as tools. The machine-readable site summary lives at /llms.txt.
One honest caveat
Tide predictions are for planning, not navigation. Wind, pressure, and river flow can push real water well away from the predicted curve — that's why every chart on Perigee overlays live observations on the prediction. For navigation, use official charts and real-time NOAA products.