A strengthening El Niño combined with long-term human-caused warming is increasing the possibility that 2026 could challenge or surpass 2024 as the hottest year measured, climate scientists told the Associated Press in an assessment published on August 5. Although 2026 ranks only third so far, behind 2024 and 2025, researchers said unusually warm oceans could soon push global air temperatures sharply higher.
Berkeley Earth climate scientist Zeke Hausfather estimated a 35% chance that 2026 will overtake 2024, up from his 7% estimate in March. Former NASA climate scientist James Hansen expects 2026 to finish ahead of the record. Scientists differ on this year's final ranking, but the AP reported broad agreement that 2027 is highly likely to become the hottest year in the modern record as El Niño's influence peaks.
Ocean conditions are central to the changing outlook. Daily global sea-surface temperatures matched 2024 levels beginning in May and have reached record levels on nearly every day since June, according to data cited by AP. Copernicus estimates that about 82% of the global ocean surface has experienced marine heatwave conditions this year. Because oceans cover more than 70% of Earth, Hansen said their heat typically takes about six weeks to appear fully in global air-temperature averages.
NOAA's Climate Prediction Center said in its July 9 update that El Niño was strengthening and had a 97% probability of continuing into early spring 2027. The agency assigned an 81% chance that it would become very strong between October and December, placing it among the largest events since records began in 1950. NOAA's experimental SPEAR system separately found that all 30 forecast runs produced a peak competitive with the strongest El Niño events of the past century, while stressing that individual regional impacts are never guaranteed.
Scientists emphasized that El Niño is not the main cause of the destructive heat, fires and other extremes already seen in 2026. Climate Central researcher Zachary Labe attributed the underlying warmth primarily to greenhouse gases from burning coal, oil and gas, with El Niño likely to add roughly 0.1°C to 0.2°C to that long-term trend. Ocean heat content, a key measure of accumulated planetary warming, has continued setting records.
The assessment comes as heatwaves affect Europe, North America, South America and India, while wildfires burn on both sides of the Atlantic. Copernicus official Samantha Burgess said the frequency and geographic reach of Europe's heatwaves were particularly unusual. NOAA plans its next formal El Niño diagnostic update for August 13, when new observations will refine the event's strength and likely effects through early 2027.
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