October 2026 Is the Hottest October on Record, 1.75°C Above Pre-Industrial Levels
The Copernicus Climate Change Service (C3S), the European Union's climate monitoring service, reported that October 2026 was the warmest October ever recorded across the world.
The average surface air temperature of the planet in October was 15.35°C. This was 0.9°C above the 1991-2020 average and 1.75°C above the pre-industrial average of 1850-1900.
October was the third month in a row more than 1.5°C above pre-industrial levels, after August and September 2026.
An exceptionally strong El Niño (a warming of the central and eastern Pacific Ocean) is adding natural heat on top of human-caused warming. The Niño 3.4 region of the Pacific hit a record monthly average of 29.94°C, 3.21°C above normal. This beat the peaks of the strong El Niño years 1982-83, 1997-98 and 2015-16.
The average sea surface temperature outside the polar regions reached 20.95°C, the highest ever for October.
C3S estimates 2026 will end 1.56°C to 1.61°C above pre-industrial levels. There is an 80% chance it will be the second-warmest year on record, after 2024, and the 2023-2026 four-year average is also expected to be above 1.5°C.
Copernicus Climate Change Service (C3S)
The Copernicus Climate Change Service, or C3S, is the European Union's official service that tracks the Earth's climate. Every month it tells the world how hot the planet was, how warm the seas were, and how much sea ice and rain there was. Its monthly reports are among the first and most quoted signals of new temperature records. You can think of it as a thermometer and record book for the whole planet, kept by the EU and open to everyone for free.
The record for October 2026, 1.75°C above pre-industrial levels, comes from C3S's monthly bulletin, which is based on the ERA5 reanalysis. C3S also gave the estimate that 2026 will likely be the second-warmest year, showing how its monthly records feed into the yearly climate picture.
El Niño–Southern Oscillation (ENSO)
El Niño–Southern Oscillation, or ENSO, is a natural climate "swing" in the tropical Pacific Ocean. Every few years, the sea surface in the central and eastern Pacific becomes unusually warm (El Niño) or unusually cool (La Niña). The winds and air pressure above the ocean change along with it. This swing changes weather around the world, and El Niño years usually push global temperatures up.
The exceptionally strong El Niño of 2026 is adding natural heat on top of human-caused warming. This is why October 2026 and the record sea temperatures broke past records so clearly.
Paris Agreement Temperature Goal and the 1.5°C Threshold
The Paris Agreement is the world's main climate treaty, adopted in 2015. Its central aim is to keep the rise in the Earth's average temperature well below 2°C above pre-industrial levels, and to try to limit it to 1.5°C. These two numbers are the yardstick against which every climate record and decision is measured.
October 2026 was the third straight month above 1.5°C, and the whole year may cross it. One hot year does not by itself break the Paris goal, but repeated years above 1.5°C show that the long-term limit is close to being crossed.
- October 2026 global surface air temperature: 15.35°C; +0.9°C over 1991-2020; +1.75°C over 1850-1900.
- Third consecutive month above 1.5°C (August, September, October 2026); the previous such run was February to April 2025.
- Sea surface temperature (outside the poles): 20.95°C, a record for October, beating October 2023.
- Niño 3.4 region: 29.94°C monthly average; record anomaly of 3.21°C.
- 2026 estimate: 1.56°C to 1.61°C above pre-industrial; 80% chance of being the second-warmest year; 20% chance of matching or beating 2024.
- 2024 remains the warmest year on record; 2026 would be only the second year above 1.5°C.
- Source agency: Copernicus Climate Change Service (C3S), run by ECMWF for the European Union.