Global Ocean Surface Temperature Breaks Record as Oregon Faces Elevated Marine Heatwave Risk
The global ocean is entering exceptional territory; El Niño is amplifying the tropical Pacific heat, and Oregon sits on the edge of a less certain- but still elevated- marine heatwave risk.
Elevated Marine Heatwave Outlook
In July 2026, marine heatwaves covered 37% of the world’s oceans, making it the second-highest level recorded for any month since observations began in 1991.
National Oceanic and Atmospheric Administration (NOAA) forecasts that global marine heatwave coverage could rise to 45% during the 2026–27 Northern Hemisphere winter, potentially the highest level in the historical record.
The tropical Pacific is at the centre of the developing heat, with a strong El Niño expected to peak during the Northern Hemisphere winter.
Source: NOAA Climate Prediction Center July 2026 Niño index values
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NOAA puts the likelihood of marine heatwave conditions in the eastern tropical Pacific at 90–100%, with high confidence.
The effects extend northward into the Northeast Pacific. Marine heatwave probabilities are forecast at 80–100% off California and Baja California, while the outlook for Oregon and Washington is lower but still elevated at 30–70%.
| Region | Likelihood | Confidence |
| Eastern Tropical Pacific | 90% to 100% | High |
| California / Baja California | 80% to 100% | High |
| Kuroshio Extension | 60% to 90% | Low to medium |
| Northeast Atlantic | 40% to 70% | Low |
| Oregon / Washington | 30% to 70% | Low to medium |
Source: NOAA Physical Sciences Laboratory August 2026 marine heatwave outlook
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NOAA describes confidence here as low to medium, making the regional outlook considerably less certain than in the tropical Pacific.
New Global Marine Heatwave Record
The broader ocean is also reaching remarkable temperatures. According to the European Commission’s Copernicus, global sea-surface temperature reached 21.1°C on 22 August 2026, narrowly exceeding the previous record of 21.09°C set in 2024.
Together, the figures point to an ocean system experiencing extraordinary, geographically widespread heat- with El Niño adding another layer of pressure to the tropical Pacific.