The year 2024 was the hottest on record at 1.55 degrees above pre-industrial levels. The World Meteorological Organization (WMO) expects this record to be broken within the next four years, with 86 percent probability. More consequential is a second figure in its May 28 report: a 75 percent probability the five-year average 2026 through 2030 will exceed the 1.5-degree mark above pre-industrial baseline. This is precisely the threshold the 2015 Paris Agreement set as a guide for global climate policy.
What the May 28 WMO report projects
The WMO's "Global Annual-to-Decadal Climate Update" appears yearly, summarizing likely temperature trends for the next five years. This year's edition names three probabilities that together sketch the coming years.
First: 91 percent probability the global annual average temperature will temporarily exceed the 1.5-degree threshold in at least one year between 2026 and 2030. Second: 86 percent probability at least one year in this period will surpass 2024's record, measured at 1.55 degrees above the 1850-1900 baseline. Third, carrying the greatest political weight: 75 percent probability the five-year average 2026 through 2030 will overall exceed 1.5 degrees.
For the Arctic, the forecast is even grimmer: the WMO expects next winter temperatures 2.8 degrees above the 1991-2020 baseline in the Arctic region, a regional warming globally unreachable today.
Why 2027 emerges as the likely record year
The forecast hinges on one natural variable: El Niño. This climate phenomenon, occurring every three to seven years, temporarily raises global temperatures through warmer Pacific waters. The WMO expects El Niño by late 2026. Its effect on global temperature typically appears with a six-to-twelve-month lag. This makes 2027 the probable candidate for the next record year.
The mechanism is familiar: a strong El Niño began in 2023, peaked in 2024 and directly contributed to that record year. La Niña, the cooling counterpart, dampened temperatures slightly in 2025. The forecast for 2027 essentially repeats this pattern, but from a higher baseline of human-caused warming.
That baseline rises continuously: each time El Niño and human warming coincide, a higher record is set than the previous cycle. In 1997-98, temperature first briefly exceeded 1.0 degree. In 2015-16, briefly topped 1.5 degrees in a single month. In 2024, for the first time in an annual average. The next cycle, forecast for 2027, begins from an even higher starting point.
What the 1.5-degree threshold means for the Paris Agreement
The 2015 Paris Agreement defines its 1.5-degree goal as long-term average warming, measured over decades, not as a single year value. One record-breaking year does not formally breach the target. The WMO emphasizes this distinction explicitly.
Yet the 75 percent likelihood for the five-year average carries different weight than a single record year: it describes not a peak but a sustained state. If five years average above 1.5 degrees, that structurally approaches what the Paris Agreement measures.
The gap between Agreement targets and actual emission paths has been known for years: according to the Climate Action Tracker, an international network of climate research institutes, current national climate pledges (NDCs) lead to roughly 2.5 to 2.7 degrees warming by 2100. WMO Secretary-General Celeste Saulo called this a "wake-up call": the distance between pledges and the necessary path is growing, not shrinking.
Two years to decision: El Niño and the emissions path
For concrete climate monitoring ahead, the WMO forecast means scientists will closely watch Pacific sea-surface temperatures from autumn 2026 onward. If the Pacific fails to cool as expected but instead warms, the path to another record accelerates.
Independent of El Niño stands a structural question the WMO report cannot answer: whether emissions fall fast enough in coming years to alter the long-term pattern. The answer depends not on climate models but on political choices in the largest emitting nations. The WMO report measures what happens if current trends continue. It describes not a force of nature but the consequences of decisions still to be made.