Sea Temperature Map

Start with the source and observation date

Open the map and select the SST layer, then select a temperature point. The legend and point card identify the source and distinguish a NOAA analysis, a retained stale observation and a labelled simulation. Read the observation date before comparing places. A page refresh or a recent cache receipt does not make an older analysis current. If a provider is unavailable, PocketWorld tries a bounded set of alternatives and keeps an available real snapshot before using simulation.

The primary product is NOAA CoastWatch daily blended sea surface temperature. The fallback order then uses preliminary OISST before the final archive. The final version is released later than the preliminary analysis; it can be valid historical data while too old for a current comparison. PocketWorld marks an observation at least two days old as stale. An old cache receipt can also trigger that state.

What the coloured points measure

The values are degrees Celsius from a gridded surface-temperature analysis, not instantaneous measurements taken at every displayed point. NOAA describes OISST's interpolation and input observations, including satellite and in-water sources. The grid can represent a broad ocean pattern even where there was no individual thermometer at that location. It does not establish the temperature at swimming depth or throughout the water column.

PocketWorld requests a sparse sample rather than every native grid cell. The requested latitude range is approximately 60 degrees south to 60 degrees north, with longitudes spanning the ocean basins. Gaps between points are not a map of missing water, and a nearby offshore point should not be moved mentally into a harbour or beach. The layer does not provide complete Arctic or northern Canadian coverage. The colour scale is a temperature key, not a comfort rating or an alert threshold.

US Atlantic, Gulf and Pacific coast questions

For a broad comparison, find an offshore point near the Atlantic, Gulf or Pacific area you are studying and retain its coordinates, source and observation time. Compare another point from the same dated product when possible. Switching between blended SST and OISST changes the analysis, so a difference should not automatically be interpreted as warming over time. This view does not calculate a historical trend, marine heatwave or ENSO index from a single snapshot.

For a specific US coastal location, use a station-based source and read its location, sensor information and time. NOAA's Coastal Water Temperature Guide notice explains that the old guide was decommissioned and points readers to operational services. Do not mistake an archived table for today's beach temperature. Our US tides and currents guide also explains why a water-height prediction or current-speed product answers a different question from temperature.

Canada and the shared Great Lakes

For Canadian Atlantic or Pacific waters within the displayed latitude range, apply the same source, date and coordinate checks. A broad ocean analysis cannot establish a reading inside an inlet or at a local swimming site. Northern locations beyond the requested range need a separate source. Our Canadian water-level guide helps locate official hydrographic products, but those height records should not be treated as temperature observations.

For local Canadian measurements, start with Environment and Climate Change Canada's marine buoy observation guide and the linked national Marine service. Choose the region and a buoy or coastal station, then check whether water temperature is actually available. Retain its station name or WMO number, position and observation time. A missing sensor value is unavailable, not zero. The example on the explanatory page is historical; open the station's current conditions for the dated reading.

For Ontario and the US states bordering the Great Lakes, use a lake-specific product rather than assuming this ocean layer covers freshwater. NOAA GLERL's Great Lakes temperature explanation describes the separate lake surface analysis. A lake-wide surface map and a nearshore station still have different spatial support. Keep the named lake, product, date and units when recording a comparison.

Keep a comparison reproducible

1. Record the selected point's coordinates, value in Celsius, product name and observation date.
2. Check whether the map says observation, stale observation, unknown cached source or simulation.
3. Use a matching dated product for regional comparisons and an appropriate local station for local questions.
4. If only simulation is available, treat its latitude-based pattern as an illustration. It has a generation time but no NOAA observation date.

This map is a geographic exploration tool. It does not assess swimming safety, issue coral alerts or replace local forecasts and official notices. Explore the separate ocean currents reference for circulation context, or return to the ship explorer for available vessel reports. Those layers do not turn a temperature sample into a current or a vessel measurement.