Swells is a real-time, AI-generated surf report for a handful of surf spots across the US. Every few hours it pulls live wave, wind, and tide data — wave height and period, swell direction, wind speed and direction, tide state, and water temperature — from Open-Meteo's Marine and Weather APIs and NOAA's Tides & Currents API, and hands that data to an AI model that writes a short, plain-language report in the voice of a local who knows the break.
Reports are cached and refreshed automatically about four times a day, so what you see is close to current conditions rather than a stale forecast — but it's still an AI summary of sensor data, not a lifeguard or a local surfer standing on the beach. Always check conditions yourself before paddling out.
Wave forecasts and ocean buoys report significant wave height — the average height of the biggest third of waves, measured in open water, well offshore. Surfers mean something different by “size”: the face of the individual wave they ride, at the beach, as it breaks. The face is reliably the bigger of the two. Waves grow as they move into shallow water before they break, and the waves worth describing are the sets, not the average of everything including the lulls.
That gap is why a forecast can say three feet on a day that looks chest-high in the water. So reports here describe size the way surfers actually talk — waist high, head high, overhead — rather than quoting a number that invites the wrong comparison. The underlying significant wave height is still what gets measured; the body-scale description is an estimate derived from it and the swell period, and it is approximate by design.
The forecast model is also corrected per spot. Global wave models resolve open ocean rather than the sandbars and shoaling each of these beaches sits behind, so they run consistently small at some spots and large at others — around 40% low at St. Augustine and 25% high on Oahu's North Shore, when checked against the nearest NOAA buoy over a month of readings. Each spot carries its own correction factor fitted against that buoy. These are refitted periodically, since they drift with the seasons.
Swells is an independent, open-source project built by Matt Whalley. The source is on GitHub. See the contact page to reach out, or the privacy page for what data is collected.