A clear read on how warm the ocean is right now — and why that matters to everyone.
OceanHeat.report tracks sea surface temperature anomalies across eight major ocean basins, updated daily from satellite observations. It translates raw climate data into something a non-scientist can understand in thirty seconds.
What this site is
It's a global ocean heat tracker. The homepage answers one question: how do current sea surface temperatures compare to normal? "Normal" is the 1991-2020 average for each basin and month — the standard reference period used by the World Meteorological Organization.
The site shows you the global picture first, then breaks it down basin by basin. Each ocean basin card displays the current temperature, the anomaly (how far above or below the long-term average), and a plain-language status — from "Near Average" to "Well Above Average." Below the basin cards, the historical trends section links to decade-scale charts showing how temperature anomalies and tropical cyclone counts have tracked together since 2015.
Why we built it
NOAA publishes some of the best ocean temperature data on earth. It's free, it's authoritative, and it's updated constantly. It's also buried in FTP directories, ERDDAP servers, and NetCDF files that require a graduate-level understanding of climate data formats to access.
Climate news tends to oscillate between "record ocean heat" headlines and silence. Neither mode gives a person a useful mental model of what's happening. We wanted a site that shows the current state of ocean heat the way a weather app shows today's forecast — factual, updated, and understandable without a tutorial.
Ocean heat is not an abstract climate metric. It drives hurricane intensity, coral bleaching, fishery collapse, and coastal weather patterns. Whether you live on the coast or a thousand miles inland, ocean temperatures shape the weather you experience, the food prices you pay, and the insurance premiums you absorb. This site exists to make that connection visible.
What's on the page
The hero verdict at the top gives you the global status in one phrase — "Warmer Than Normal," "Slightly Warm," "Near Average," or their counterparts — driven by the average anomaly across all eight basins. The number next to it is the global sea surface temperature anomaly in degrees Celsius, relative to the 1991-2020 baseline.
The status panel summarizes how many basins are running above average and, if your browser shares location data and you're near a coast, adds a line showing conditions near you. If you're inland or decline location access, the panel still works — it leads with the global picture.
Basin cards cover eight ocean regions: North Atlantic, Gulf of Mexico, Mediterranean Sea, Western Pacific, Indian Ocean, South Pacific, South Atlantic, and Arctic Ocean. Each card pulls live SST data from the Open-Meteo Marine API and computes the anomaly against its 1991-2020 monthly baseline. The status label and color coding update automatically.
Historical trends link to per-basin chart pages showing annual sea surface temperature anomalies alongside tropical cyclone counts (named storms, hurricanes/typhoons, and major hurricanes) from 2015 to 2025. These charts use NOAA OI SST V2.1 data for temperature and NHC, JTWC, and WMO records for storm counts.
The "What This Means" section connects ocean heat to real-world consequences — hurricane fuel, coral bleaching thresholds, and the ENSO cycle — with links to in-depth guides for each topic.
Data sources
Live sea surface temperature readings come from the Open-Meteo Marine API, which aggregates satellite and reanalysis data and provides fast, free access without API keys.
Monthly baselines (the "normal" each reading is compared against) are computed from the NOAA OI SST V2.1 dataset via ERDDAP, averaged over the 1991-2020 reference period. This is the same baseline period used by NOAA, the WMO, and most national meteorological services for climate normals.
Historical temperature data for the trend charts also comes from NOAA OI SST V2.1. Tropical cyclone counts come from the National Hurricane Center (Atlantic), Joint Typhoon Warning Center (Western Pacific and Indian Ocean), and WMO regional reports (South Pacific).
All data sources are free and publicly operated. Data is aggregated and cached by a Cloudflare Worker that refreshes every three hours — fast enough to reflect meaningful changes, slow enough to respect upstream rate limits.
How anomalies work
A sea surface temperature anomaly is simply the difference between what the ocean temperature is right now and what it normally is for this location and time of year. A reading of +0.8°C means the water is eight-tenths of a degree warmer than the 30-year average for that basin in the current month.
That sounds small. It isn't. The ocean has enormous thermal mass — it takes a staggering amount of energy to shift its temperature even slightly. A sustained +0.5°C anomaly across a major ocean basin represents more thermal energy than all of human civilization uses in a year. When basins run +1.0°C or higher above baseline, the downstream effects on weather systems, marine ecosystems, and atmospheric circulation are significant and measurable.
What this site is not
This is not a forecast. It shows current conditions and historical trends — it does not predict what ocean temperatures or storm activity will do next. For tropical cyclone forecasts, consult the National Hurricane Center. For climate projections, see NOAA's Climate.gov.
This is not emergency management guidance. If you're in the path of a tropical cyclone or other marine weather event, follow your local emergency management agency's instructions — not this site.
The guides
Beyond the tracker, the site has plain-language guides covering what SST is and why it matters, marine heat waves, coral bleaching, how ocean heat fuels hurricanes, and the ENSO cycle. They're all at oceanheat.report/guides.
Part of a network
This site is part of a small network of seasonal condition trackers, each built to answer one question clearly. The hurricane tracker is at isithurricaneseasonyet.com. Others cover allergy season, mosquito season, flu season, and RSV season.
Get in touch
Data corrections, bug reports, feedback, or questions: [email protected], or use the contact form.