Global Ocean Surface Temperatures Hit 20.98 C in June, Matching Some Earlier Pacific Records

Global average sea surface temperatures reached 20.98 °C in June, the highest monthly value on record, according to the European Union’s Copernicus Marine Service. The reading surpassed the previous June records set in 2023 and 2024. Average temperatures for the first half of 2026 stood at 20.04 °C.

Marine heat waves covered about 82 percent of the world’s oceans during the January–June period. The Mediterranean recorded its hottest June on record at 24.3 °C, with marine heat waves affecting 98 percent of the basin. The tropical Pacific posted 27.26 °C in June and matched its 2016 record for the January-to-June period.

Carlo Buontempo, director of the Copernicus Climate Change Service, stated that ocean temperatures at these levels and an approaching El Niño increase the chance of additional records in coming months. Simon Van Gennip, lead oceanographer for the Copernicus Marine Service, said the combination of El Niño and continued greenhouse-gas emissions will likely place 2026 among the warmest years recorded.

Oceans absorb roughly 90 percent of the excess heat from greenhouse-gas emissions.

Warmer waters increase atmospheric moisture, expand in volume, and create conditions that can bleach coral reefs during prolonged heat events.