Data Sources

Every data point on this site comes from an authoritative public source. Here they are.

Tides & Water Temperature

Tide predictions, water temperature, and current data come from the NOAA Center for Operational Oceanographic Products and Services (CO-OPS). Data is pulled per beach from the nearest monitoring station via the public CO-OPS API.

Weather Forecasts & Alerts

Forecasts, current conditions, and active alerts come from the National Weather Service API. This is the same feed behind weather.gov.

Swim Advisories & Water Quality

Bacteria-level swim advisories come from the state programmes that issue them. We read 16 of them directly, covering 256 of the 510 beaches on this site:

• Alabama — Coastal Alabama Beach Monitoring (ADEM)
• Delaware — Delaware DNREC Recreational Water Monitoring
• Indiana — Indiana IDEM BeachAlert
• Louisiana — Louisiana Dept. of Health Beach Monitoring
• Maryland — Maryland Healthy Beaches (Maryland Department of the Environment)
• Massachusetts — Massachusetts Dept. of Public Health Beach Water Quality
• Mississippi — Mississippi DEQ Beach Monitoring
• New Jersey — NJDEP Cooperative Coastal Monitoring Program
• New York — New York State Department of Health
• North Carolina — NC DEQ Recreational Water Quality
• Ohio — Ohio Dept. of Health BeachGuard
• Rhode Island — Rhode Island Dept. of Health Beach Monitoring
• South Carolina — SC Dept. of Environmental Services Beach Monitoring
• Texas — Texas Beach Watch (Texas General Land Office)
• Virginia — Virginia Dept. of Health Beach Monitoring
• Wisconsin — Wisconsin DNR Beach Health

Each state publishes on its own schedule — typically weekly during the swim season, and sooner after heavy rainfall or a bacteria exceedance. We keep each agency's own wording rather than translating it into a single verdict, because the vocabularies genuinely differ: Texas publishes a bacteria level, Massachusetts calls an advisory "posted", South Carolina separates a long-term advisory from an emergency closure.

The remaining 254 beaches are in states that either publish no machine-readable current status or whose terms of use prohibit automated access. We do not scrape those. On those beaches we show USGS Water Quality Portal bacteria sampling instead, always labelled with the sample date so an old reading is never presented as a current verdict.

Sunrise & Sunset

Calculated locally using the standard NOAA solar position algorithm. No API call needed.

Beach Metadata

Static information about each beach — address, parking, amenities, dog rules, entry fees — is manually curated from official park websites, county pages, and visitor centers. If you see outdated or incorrect info, email us.

The Beach Day Score

The 0-100 score combines current water temperature, air temperature, wind speed, rain probability, active weather alerts, and swim advisories into a single rating. The formula is opinionated — it assumes you want to actually get in the water — but the underlying data is transparent and the methodology is linked from every beach page.

Update frequency

The site is statically generated and rebuilds on a scheduled cadence. Conditions you see are typically within the last hour.