Why the Odds Have Surged

The primary driver of this revised forecast is an unusually powerful El Niño that started developing in June 2026 . This natural climate pattern, characterized by warming of the Pacific Ocean, has intensified much faster than earlier predictions. Berkeley Earth scientist Zeke Hausfather noted that the El Niño is coming on so strong that it has significantly raised the probability of record global heat in the second half of the year . This El Niño is projected to peak at around 3.6°C above normal, which would be a historically large event .

The surge to 69% marks a stark increase from earlier in 2026. The chance of a record year was estimated at just 2.5% in May and 5% in March . By July 23, Berkeley Earth's own update still showed only a 12% probability . A mid-July analysis by Carbon Brief had placed the chance at 35% . The updated 69% figure reflects the rapid revision of El Niño forecasts in the weeks that followed.

Berkeley Earth notes that the most likely outcome for 2026 had been a second-place finish, a 67% probability in their June update . However, the rapidly changing outlook has made a record-breaking year the new upper bound.

A 'One-Two Punch' of Climate Change and El Niño

Scientists describe the current situation as a "one-two punch" effect, where the natural warming influence of El Niño is superimposed on the long-term warming trend caused by human greenhouse gas emissions . This combination is creating conditions for extreme heat events worldwide.

Concurrent Extreme Heat Events

The forecast for record global heat is already being realized in the form of punishing regional heatwaves.

East Asia

• South Korea: The country recorded its highest temperature since modern records began in 1904. On August 2, the southeastern city of Yangsan reached 42.5°C (108.5°F) . This was the fifth consecutive day temperatures in Yangsan exceeded 40°C (104°F) . The heat was so intense that Seoul issued its first-ever "severe heatwave warning" under a new advisory system, and nearly 300 people were hospitalized due to heat-related illnesses . The extreme heat spread across the entire Korean Peninsula, with North Korean state media reporting temperatures approaching 40°C (104°F) in parts of the country .
• Japan: Temperatures reached 40°C or higher at multiple locations. The country recorded its first-ever 'kokushobi', or 'cruelly hot day', a new category for temperatures above 40°C .
• Hong Kong: The city also experienced punishing record heat through the summer .

United States

• Record-Breaking July: July 2026 was the hottest month ever recorded in the contiguous United States, with an average temperature 3.3°F (1.8°C) higher than the 20th-century average .
• Widespread Records: A North American heatwave in July broke or tied all-time records in multiple cities. Atlantic City, New Jersey, tied its all-time record of 106°F (41°C) . Washington, D.C., reached 102°F (39°C), and other cities like Philadelphia, Boston, and New York also set daily records .
• Western U.S. Heatwave: In early August, the National Weather Service forecast Mojave Desert highs of 110–120°F (43–49°C) with Major to Extreme HeatRisk, issuing Extreme Heat Warnings across the western U.S. . Peak heat conditions were forecast through August 8–9 . Above-normal temperatures were forecast coast-to-coast through mid-August .

The Outlook for 2027: Even Hotter

Perhaps the most sobering finding from the Berkeley Earth analysis is the outlook for next year. Regardless of whether 2026 sets a record, scientists expect 2027 to be even hotter . The full warming influence of the current El Niño tends to manifest most strongly in the year following its peak . Because El Niño started in June 2026, most of its warming impact will be felt in 2027, meaning the global average temperature for 2027 could "clear the old record by a wide margin" . Across 14 forecasting models, the odds of a new record in 2027 are estimated at around 90% .

Why the Odds Have Surged

The primary driver of this revised forecast is an unusually powerful El Niño that started developing in June 2026 . This natural climate pattern, characterized by warming of the Pacific Ocean, has intensified much faster than earlier predictions. Berkeley Earth scientist Zeke Hausfather noted that the El Niño is coming on so strong that it has significantly raised the probability of record global heat in the second half of the year . This El Niño is projected to peak at around 3.6°C above normal, which would be a historically large event .

The surge to 69% marks a stark increase from earlier in 2026. The chance of a record year was estimated at just 2.5% in May and 5% in March . By July 23, Berkeley Earth's own update still showed only a 12% probability . A mid-July analysis by Carbon Brief had placed the chance at 35% . The updated 69% figure reflects the rapid revision of El Niño forecasts in the weeks that followed.

Berkeley Earth notes that the most likely outcome for 2026 had been a second-place finish, a 67% probability in their June update . However, the rapidly changing outlook has made a record-breaking year the new upper bound.

A 'One-Two Punch' of Climate Change and El Niño

Scientists describe the current situation as a "one-two punch" effect, where the natural warming influence of El Niño is superimposed on the long-term warming trend caused by human greenhouse gas emissions . This combination is creating conditions for extreme heat events worldwide.

Concurrent Extreme Heat Events

The forecast for record global heat is already being realized in the form of punishing regional heatwaves.

East Asia

• South Korea: The country recorded its highest temperature since modern records began in 1904. On August 2, the southeastern city of Yangsan reached 42.5°C (108.5°F) . This was the fifth consecutive day temperatures in Yangsan exceeded 40°C (104°F) . The heat was so intense that Seoul issued its first-ever "severe heatwave warning" under a new advisory system, and nearly 300 people were hospitalized due to heat-related illnesses . The extreme heat spread across the entire Korean Peninsula, with North Korean state media reporting temperatures approaching 40°C (104°F) in parts of the country .
• Japan: Temperatures reached 40°C or higher at multiple locations. The country recorded its first-ever 'kokushobi', or 'cruelly hot day', a new category for temperatures above 40°C .
• Hong Kong: The city also experienced punishing record heat through the summer .

United States

• Record-Breaking July: July 2026 was the hottest month ever recorded in the contiguous United States, with an average temperature 3.3°F (1.8°C) higher than the 20th-century average .
• Widespread Records: A North American heatwave in July broke or tied all-time records in multiple cities. Atlantic City, New Jersey, tied its all-time record of 106°F (41°C) . Washington, D.C., reached 102°F (39°C), and other cities like Philadelphia, Boston, and New York also set daily records .
• Western U.S. Heatwave: In early August, the National Weather Service forecast Mojave Desert highs of 110–120°F (43–49°C) with Major to Extreme HeatRisk, issuing Extreme Heat Warnings across the western U.S. . Peak heat conditions were forecast through August 8–9 . Above-normal temperatures were forecast coast-to-coast through mid-August .

The Outlook for 2027: Even Hotter

Perhaps the most sobering finding from the Berkeley Earth analysis is the outlook for next year. Regardless of whether 2026 sets a record, scientists expect 2027 to be even hotter . The full warming influence of the current El Niño tends to manifest most strongly in the year following its peak . Because El Niño started in June 2026, most of its warming impact will be felt in 2027, meaning the global average temperature for 2027 could "clear the old record by a wide margin" . Across 14 forecasting models, the odds of a new record in 2027 are estimated at around 90% .