August 2026 is the warmest August on record and ties the hottest month ever measured

August 2026 was the warmest August in the Copernicus Climate Change Service ERA5 record, with a global mean surface air temperature of 16.96°C. That is 0.85°C above the 1991-2020 average for the month and above the previous joint August marks of 16.82°C set in 2023 and 2024.

The same month also ties the hottest calendar month ever recorded. July 2023 stood at 16.95°C. The gap is less than 0.01°C. August 2026 was 0.06°C warmer than July 2026, which is unusual. July is normally the warmest month of the year. In ERA5, which starts in 1940, August beat July in the same year only in 1945, 1951, 1955 and 1985.

NOAA’s National Centers for Environmental Information, using a different baseline, called August 2026 the warmest August in its 1850-2026 series, 1.32°C above the twentieth-century average and 0.08°C above the tied 2023 and 2024 Augusts. It was the 48th August in a row above that twentieth-century mean. The last cooler-than-average August in that dataset was 1978. All ten of the warmest Augusts have arrived since 2016.

The ocean ran hotter than the calendar allows

Extra-polar daily sea surface temperature, measured between 60°S and 60°N, reached 21.11°C on 24 and 25 August. That beat the previous all-time daily mark of 21.09°C set in March 2024. The extra-polar ocean usually peaks in March and April. Hitting a record in late August means the water did not follow the usual seasonal script.

Copernicus said daily extra-polar SST has been the highest recorded for each calendar day since 19 June. The heat was not confined to the equatorial Pacific. Large areas of other basins were also at record levels for the date. NOAA said global ocean temperature set a new monthly high while land was near-record warm. The Northern Hemisphere had its warmest summer. The Southern Hemisphere had a near-record warm winter. Arctic and Antarctic sea ice extent ran below average.

El Niño on a steep climb

A strong El Niño is building underneath those numbers. Berkeley Earth, in its July update, put the daily Niño-3.4 index near +2.7°C on a trend-removed basis, warmer at this point in the calendar than the 1997 and 2015 events. Multi-model forecasts it cited pointed to a peak near +4.0°C around November, above the +2.75°C peak of 2015-16. NOAA has an El Niño advisory in place and has assigned high odds that the event stays very strong through northern winter.

Copernicus noted that the 2023 El Niño lifted global anomalies sharply in the last four months of that year. If the last third of 2026 behaves like 2023, the annual mean would sit close to 2024, the current warmest year. Forecasts also say the 2026 event may outgrow 2023. That is a statement about the Pacific oscillator sitting on top of a climate that has already delivered ten record or near-record Augusts in a decade.

Scientific American, working from the Copernicus release, put August at about 1.65°C above the pre-industrial mean used in Paris Agreement debates. The United Nations said last week that a consistent breach of 1.5°C is now unavoidable. One month does not define that breach. A month that is both the hottest August and statistically tied with the hottest month ever does move the running mean.

What the maps showed on land

NOAA mapped departures of at least 2.0°C across parts of Europe, Africa, Asia, Antarctica, and sections of both American continents, plus a wide belt of the central and eastern tropical Pacific consistent with El Niño. Western Europe and the United States had their hottest summers in the Copernicus and NOAA tallies. Nineteen tropical storms put global cyclone activity above average for the month.

None of those regional bullets require a new theory. They require a reader to hold two facts at once. The long-term rise in greenhouse gases sets the floor. A fast El Niño lifts the floor another notch, and August 2026 sat on that notch. The next test is whether September through December follow the 2023 script. The agencies will publish those months the same way they published this one: a number to two decimals, a baseline, and a rank.