On August 22, 2026, the global average sea surface temperature reached 21.10 degrees Celsius, surpassing the previous all-time record of 21.09C set in March 2024. The milestone, confirmed by the Copernicus Climate Change Service using the ERA5 dataset stretching back to 1979, marks the highest daily global mean sea surface temperature ever measured across the 60S to 60N band.

The anomaly represents a departure of approximately 0.67C to 0.95C above historical baseline averages. NOAA reported that July 2026 global ocean temperature was the highest on record for July at 1.02C above average, establishing a clear correlation between the strengthening El Nino event and ocean extremes.

NOAA Climate Prediction Center said El Nino is strengthening, with a greater than 90 percent chance of a very strong event during Northern Hemisphere fall and winter 2026-27. Marine heatwaves now affect approximately 42 percent of global ocean surface area, according to satellite and in-situ measurement networks.

West Coast waters are experiencing a large marine heatwave running roughly 1.7C to 2.2C above normal, according to NOAA Fisheries. Ocean heat content continues to build as the world ocean absorbs more than 90 percent of excess heat from greenhouse gas warming, with cascading effects on fisheries, coastal weather patterns, and marine ecosystems.

Warmer surface layers reduce vertical mixing in some regions, preventing nutrient cycling that supports lower food web levels. Tropical coral reefs are experiencing persistent thermal stress with recurring bleaching events. Scientists warn these conditions are expected to persist as El Nino strengthens through the Northern Hemisphere fall and winter, with potential impacts on hurricane season intensity, regional precipitation patterns, and long-term ecosystem health.

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