Satellite sea surface temperature (SST) charts are one of the most useful tools for offshore anglers. They show where warm and cool water meet, where currents are flowing, and where bait-rich water is concentrated. Reading them before a trip helps you run straight to productive water instead of searching blind.
What SST charts show
SST charts display surface water temperature as colors. Sharp color changes on the chart mark temperature breaks, the edges where fish often concentrate. See trolling temperature breaks.
Chlorophyll charts
Chlorophyll charts show plankton levels. Green, high-chlorophyll water holds bait; clear blue, low-chlorophyll water holds predators. The edge between them is a color change and often a strong fishing spot.
Altimetry
Some services show sea surface height, which can reveal eddies and current flows that do not always show up clearly on SST. Warm-core eddies and current edges are prime areas for tuna and billfish.
How to read a chart
- Find the breaks: look for tight bands where color changes quickly.
- Check the temperature range: match it to your target species' preferences.
- Look for structure: breaks that line up with canyons, ledges, or seamounts are especially productive.
- Compare days: watching charts over several days shows which way edges are moving.
Clouds
Clouds block satellite temperature readings, leaving gaps in the chart. Composite charts combine several days of images to fill in gaps, but they may be less current. Check the image date.
Planning a route
Mark the best breaks on your plotter before leaving. Plan to troll along them, starting with the closest promising edge. Confirm conditions with your temperature gauge and your eyes when you arrive.
Combine with what you see
Charts are a starting point. Once you are on the water, look for birds, bait, weed lines, and marks on the sounder. See reading birds offshore and using a fish finder offshore.
