Will 2026 be the hottest calendar year on record globally (surpassing 2024, the current record holder)?

probability: 32%

rationale:

Current Trajectory: Through the first seven months of 2026, global temperatures are running noticeably behind the record-setting pace of 2024. Across major datasets, January to July has generally ranked as the third-warmest start to a year yaleclimateconnections.org. In the Copernicus ERA5 dataset, 2026 has accumulated a deficit of roughly 0.15°C compared to the same period in 2024 carbonbrief.org. While July 2026 was exceptionally hot—effectively tying July 2024 in several datasets and reaching joint-second warmest in ERA5 climate.copernicus.eu—it did not meaningfully close the year-to-date gap. For 2026 to surpass 2024 outright, the August through December anomalies would need to exceed those of 2024 by approximately 0.15°C to 0.25°C, requiring consecutive months at or above all-time monthly records.

The El Niño Upside Risk: The primary factor keeping a new record within reach is a rapidly intensifying El Niño. After a brief La Niña and neutral period, equatorial Pacific sea surface anomalies surged, with the Niño3.4 index reaching approximately +2.7°C by early August berkeleyearth.org. Current multi-model climate forecasts project a peak near +4.0°C in November, which would comfortably make this the strongest El Niño in the observational record 2 sources. This unprecedented oceanic heat provides a massive upward push to late-year global temperatures.

The ENSO Lag Effect: However, global surface temperatures typically lag the ENSO index by three to five months theclimatebrink.com. Because the current El Niño is expected to peak in November or December, the bulk of its atmospheric warming impact will land in 2027, rather than inside the 2026 calendar year. While the late-2026 anomalies will undoubtedly be elevated, the lag heavily mitigates the chance that they will rise fast enough—and early enough—to fully erase the accumulated January–July deficit.

Dataset Divergence and the Consensus Hurdle: Even if late-year temperatures spike, 2026 faces a strict structural hurdle: a formal record requires a consensus of major datasets or a definitive WMO consolidated statement. Evaluating the stringent requirements for a multi-dataset consensus record alongside related global temperature trajectories tightly constrains the likelihood of an outright 2026 record. There is significant heterogeneity among the monitoring bodies. Surface-station datasets like NASA GISTEMP and Berkeley Earth recorded a relatively lower peak for 2024, making them much more likely to show 2026 as a new record, with internal statistical probabilities for these specific datasets near 65–69% 2 sources. Conversely, reanalysis datasets like ERA5 and JRA-3Q, along with NOAA and HadCRUT, have a much higher bar to clear, with their specific likelihoods of a 2026 record hovering between 9% and 35% theclimatebrink.com. This divergence makes a split verdict highly plausible. Without a clear majority across all major datasets, the WMO is likely to declare 2026 "one of the warmest" rather than the outright record holder, leaving the probability of a definitive new record at 32%.