Will 2026 be the hottest year on record?

probability: 19%

rationale:

Summary In determining whether 2026 will rank as the hottest year on record according to the NASA GISS Land-Ocean Temperature Index (No_Smoothing), the central challenge is weighing a relatively cool start to the year against a rapidly developing, potentially historically strong El Niño. The current record holder is 2024, which recorded an annual anomaly of 1.29°C above the 1951-1980 baseline data.giss.nasa.gov. Through the first four months of 2026, global temperatures have averaged approximately 1.20°C data.giss.nasa.gov. This places 2026 significantly behind 2024's blistering early-year pace of approximately 1.345°C data.giss.nasa.gov. To tie or break the record, the remaining eight months of 2026 would need to average roughly 1.335°C data.giss.nasa.gov, an extraordinarily high threshold that would require the latter portion of the year to substantially outperform the late months of 2024. The primary catalyst that could drive temperatures to this required level is an exceptionally strong, emerging El Niño. Recent data indicates an 82% chance of El Niño development by May-July 2026, and a 96% chance of it persisting through the winter 2 sources. However, because global atmospheric temperatures typically lag changes in the El Niño-Southern Oscillation (ENSO) by three to six months, the most extreme warming effects are highly likely to peak in 2027 rather than 2026. Therefore, while a late-year surge in 2026 is virtually guaranteed, the mathematical deficit accumulated between January and April remains steep. Several quantitative climate outlooks align with this balance of evidence, broadly suggesting approximately a one-in-five chance of a new record carbonbrief.org. Given the confirmed early-year data and the established lag in ENSO teleconnections, evidence suggests 2026 will most likely finish as the second-warmest year on record, passing the baton to 2027 for a more probable record-breaking event.

Strongest Arguments for Yes

• A rapidly intensifying El Niño is currently emerging, with some projections indicating it could reach "super" status (Nino3.4 anomaly of 3°C or more) by December 2026 2 sources. An unprecedented warming of the equatorial Pacific could transfer heat to the atmosphere faster than historical analogs suggest, driving up the global average in the second half of the year.
• Prominent climate research explicitly projects 2026 will surpass 2024, arguing that sea surface temperatures in 2026 are consistently warmer than in 2023 at the same ENSO phase [84e149, 0bba6c, 8e0a2]. Maintaining this margin could theoretically allow 2026 to exceed 2024 by 0.06°C [8e0a2].
• The underlying, long-term global warming trend of approximately 0.02°C per year provides an ever-increasing baseline, slightly elevating the chances of any subsequent year breaking the record regardless of specific natural variability.

Strongest Arguments for No

• The significant January-April temperature deficit makes catching 2024 mathematically improbable. Through April, 2026 anomalies averaged just 1.20°C compared to 2024's 1.345°C data.giss.nasa.gov, meaning the rest of the year must average roughly 0.08°C hotter than the same period in 2024 just to tie the record data.giss.nasa.gov.
• Global surface temperatures typically lag peak El Niño ocean warming by 3 to 6 months. This physical reality dictates that the maximum atmospheric heat generated by the current ENSO cycle will manifest in early-to-mid 2027, arriving too late to boost the 2026 annual mean sufficiently carbonbrief.org.
• A strong consensus of statistical and institutional outlooks, including analyses from Carbon Brief carbonbrief.org, NOAA ncei.noaa.gov, and the UK Met Office metoffice.gov.uk, predict 2026 is most likely to be the second-warmest year, placing the probability of a new record well below 30%.

Key Uncertainties

• El Niño Development Speed and Intensity: If the emerging El Niño intensifies with unprecedented speed and breaches the 3°C anomaly mark earlier than expected livescience.com, the associated atmospheric warming could arrive fast enough to erase the early-year deficit. Conversely, a slower development ensures the warming shifts entirely to 2027.
• Data Adjustments and Rounding: The resolution depends strictly on the exact NASA GISS No_Smoothing annual table value. Minor variations, rounding effects, or late-year data anomalies could tip the final decimal points, potentially creating a tie or marginal victory if temperatures track exceptionally close to the 1.29°C threshold.