Guides

Understanding ocean heat.

Plain-language explanations of the science behind the numbers on this site — what sea surface temperature anomalies mean, why they matter, and how ocean heat connects to the weather, ecosystems, and climate patterns that affect everyone.

Fundamentals

Fundamentals Sea surface temperature: what it is and why it matters The basics — how sea surface temperature is measured, what the anomaly means, and why a degree or two changes everything. Read guide →

Phenomena

Phenomena Marine heat waves: the underwater fires Persistent extreme ocean temperatures that devastate fisheries, kill coral, and alter weather patterns hundreds of miles inland. Read guide → Climate Patterns ENSO and ocean heat El Nino, La Nina, and the global temperature seesaw — how the equatorial Pacific drives weather patterns worldwide. Read guide →

Impacts

Ecosystems Coral bleaching: when the reef turns white How thermal stress expels the symbiotic algae that give coral its color — and its life. Read guide → Storms How ocean heat fuels hurricanes Warm water is the engine. The 26.5°C threshold, rapid intensification, and why ocean heat content matters more than surface temperature alone. Read guide →

Data

Historical Trends Basin-by-basin temperature and storm trends Interactive charts showing sea surface temperature anomalies alongside tropical cyclone counts for all eight tracked ocean basins, 2015 to 2025. View charts →