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About Sea Temps

Sea Temps shows the daily sea surface temperature near 283 named beaches and coastal towns in Ireland, England, Scotland, Wales and Northern Ireland. Each page has the latest reading, a 30-day chart, the normal for the date and month, a general wetsuit guide and nearby places.

Where the data comes from

Sea temperature. The Multi-scale Ultra-high Resolution (MUR) sea surface temperature analysis, version 4.1, produced by NASA's Jet Propulsion Laboratory (JPL) and distributed through NOAA's CoastWatch ERDDAP server (dataset jplMURSST41). It blends several satellite sensors into a daily global grid with cells about 1 km across. The data licence says it may be used and redistributed for free, and that it is not intended for legal use because it may contain inaccuracies.

Normals. The MUR daily climatology for 2003 to 2014 (dataset jplMURSST41clim), the average for each day of the year. The monthly table on each page averages these daily values.

Places. Names and coordinates from GeoNames, used under the Creative Commons Attribution 4.0 licence. For each place the site uses the nearest grid cell that the analysis treats as open sea.

How accurate is it?

The analysis estimates the temperature of the sea surface layer over a whole grid cell. Water at the shoreline, in shallow bays, estuaries and rock pools can be several degrees warmer on a sunny day or colder after rain or wind. Readings are usually one to two days old. Use the numbers as a guide to conditions and trends, not as an exact measurement.

The wetsuit guide is a general rule of thumb based only on water temperature. Comfort depends on wind, air temperature, time in the water and the person.

This site is not safety advice. Check local lifeguard, coastguard and water safety guidance before swimming.

How it is built

The site and the scripts that fetch and process the data were built with help from AI tools. The temperatures are not written or changed by AI: they come straight from the datasets above. Pages are rebuilt automatically once a day when a new reading is available. If the data cannot be fetched, the previous day's pages stay up.

The site is free to use. There are no ads, no sign-ups and no tracking cookies. Visits are counted with Cloudflare Web Analytics, which does not use cookies.