Global sea surface temperatures reach record high for June, surpassing 2023 and 2024 levels

Record-breaking temperatures

Global sea surface temperatures in June 2026 have climbed past the previous highs for this time of year, set in 2023 and 2024. The Copernicus Climate Change Service (C3S) recorded a daily average of 20.86°C on 21 June, edging above the 20.83°C observed in the two prior years. The Copernicus Marine Service (CMEMS) independently reported 21°C on the same day, 0.1°C warmer than earlier records. The back-to-back record years underline a persistent warming trend that scientists link to climate change and the onset of El Niño.

“Current conditions could indicate the start of a new phase that takes us, once again, into uncharted territory.”

202320.83

202420.83

202620.86

2023

20.83 °C

2024

20.83 °C

2026

20.86 °C

Data from the article text

El Niño intensifies the heat

June 2026 also marks the official emergence of an El Niño event in the tropical Pacific. The natural climate phenomenon, characterised by warmer-than-usual waters, is forecast to strengthen in the coming months. The C3S seasonal prediction models suggest an intensity not seen in decades. Combined with the background signal of climate change, the event is pushing ocean temperatures into record territory, with the global extrapolar ocean already running 0.35°C to 0.73°C above the long-term average over the past three years. In June 2024, the global sea surface also set a record, but then El Niño was weakening and the Pacific was returning to neutral conditions. The current repetition, this time with a strengthening El Niño, suggests the ocean may be entering a sustained warm phase.

Cascading weather and ocean impacts

Warmer seas feed into the atmosphere, keeping it heated longer and supplying additional energy to storms. Higher evaporation rates increase the risk of extreme rainfall and flooding, while the thermal expansion of water contributes to sea level rise and accelerates ice melt. Marine heatwaves become more frequent and intense, disrupting ecosystems, fisheries and coastal economies. The Copernicus statement warns that these changes can amplify heat extremes on nearby land.

“Higher ocean temperatures keep the atmosphere warm for longer, supply extra energy to storms and raise evaporation, increasing the risk of extreme precipitation and flooding. Ocean warming also contributes to sea level rise and ice melt, and pressures marine ecosystems.”

Watching for a signal or a blip

Scientists at Copernicus are monitoring whether the June spike is a temporary anomaly or an early sign of persistently elevated temperatures. Carlo Buontempo, C3S director, added that the robust, open data from both Copernicus services reaffirm the need for policies that protect the marine environment. The same datasets, he noted, help track whether this excess heat dissipates or deepens over the months ahead.