WMO Forecast: 70% Chance Global Average Temperature Will Breach 1.5°C Threshold Between 2025 and 2029

The World Meteorological Organization (WMO) has released its latest decadal climate forecast, projecting a 70% probability that the global average temperature will breach the 1.5°C threshold for the entire five-year period between 2025 and 2029. This represents a striking shift in the statistical data; just two years ago, the forecasted probability for a five-year breach stood at 32%, before climbing to 47% in 2024. The updated modeling provides one of the highest-resolution looks yet at near-term planetary warming, offering policymakers a precise evidence pack for the coming half-decade.[1][3]

The core claim of the WMO report centers on a specific temperature anomaly range. According to the synthesized data, the annually averaged global mean near-surface temperature for each year through 2029 is predicted to land between 1.2°C and 1.9°C above the 1850–1900 pre-industrial baseline. Furthermore, the models show an 86% certainty that at least one individual year in this window will exceed the 1.5°C mark, and an 80% chance that at least one year will surpass 2024 as the hottest year on historical record.[1][2]

The methodology behind these forecasts relies on an unprecedented synthesis of dynamic model projections. The WMO aggregates data from multiple designated Global Producing Centres, combining models that assess both human-driven greenhouse gas forcing and short-term natural climate variability. By running thousands of simulations, researchers generate a probabilistic spread that quantifies the exact likelihood of various temperature outcomes over the next five years.[1]

The certainty of these near-term projections is heavily bolstered by the models' successful "hindcasting" capabilities. Before forecasting the future, these algorithms are fed historical climate data and asked to predict known past events. Because the current generation of models accurately recreates the temperature anomalies of the past two decades, forecasters assign high confidence to their near-term predictive accuracy.

However, a crucial distinction in the WMO's evidence pack is the difference between a temporary overshoot and a permanent breach of the 2015 Paris Agreement. The Paris Agreement's 1.5°C "North Star" target is defined by a long-term climatological average, typically measured over a 20-year period, rather than a single year or a five-year spike. Climate modelers emphasize that while the 2025–2029 forecast indicates a high likelihood of a temporary exceedance, it does not mean the diplomatic goal is mathematically dead.[1][3]

Despite this technical distinction, the data clearly illustrates that temporary exceedances are occurring with increasing frequency as the underlying baseline temperature rises. The WMO's central estimate for the 20-year average warming spanning 2015 to 2034 is now projected at 1.44°C, placing the long-term trendline perilously close to the threshold. This rolling average smooths out the noise of individual hot or cold years, revealing the undeniable upward trajectory of the climate system.[1][2]

Independent climate analysts have extrapolated from the WMO data to estimate when the permanent 20-year crossing date might occur. If global warming continues at its historical rate of 0.2°C per decade after the 2029 forecast window, researchers estimate the permanent 1.5°C breach could arrive as early as 2028 or 2030. While this involves a degree of assumption about post-2029 emissions, it underscores how rapidly the window for preventative mitigation is closing.

In the interest of transparent uncertainty, the WMO report explicitly models the role of natural climate variability. Phenomena such as the El Niño-Southern Oscillation (ENSO) and the Atlantic Multidecadal Variability (AMV) introduce significant noise into near-term forecasts. For instance, an El Niño event predicted for the end of 2026 increases the probability that 2027 could break all previous temperature records, while a transition to a La Niña pattern could temporarily suppress global averages.

Forecasters also address edge cases that could alter the five-year trajectory, such as a major volcanic eruption. Volcanic events release massive quantities of sunlight-reflecting sulfur dioxide into the stratosphere, which can cause a large but temporary drop in global temperatures. While such an event would change the forecast significantly, physicists note it is highly unlikely that natural variability alone will fortuitously intervene to offset the broader anthropogenic warming trend.

Beyond the global average, the WMO's data pack provides high-confidence forecasts for regional climate shifts, with the strongest evidence pointing toward polar amplification. The models predict that Arctic warming over the next five extended winters will outpace the global average by a staggering factor of 3.5. This translates to a projected 2.4°C anomaly in the Arctic relative to the 1991–2020 baseline.[1][3]

The physical consequences of this localized warming are already mapped in the data. The forecast projects further high-probability reductions in sea-ice concentration across the Barents, Bering, and Okhotsk seas. Because melting ice exposes darker ocean waters that absorb more solar radiation, this regional anomaly creates a feedback loop that further accelerates global temperature rise.[1]

The models also evaluate shifting precipitation patterns with moderate-to-high confidence, offering critical foresight for agricultural and economic planning. For the May-to-September periods through 2029, the data suggests anomalously wet conditions will likely develop in the African Sahel and northern Europe. Conversely, the Amazon region and parts of South Asia face an elevated risk of sustained drier conditions, increasing the probability of intense droughts.[1][2]

For policymakers and climate diplomats, this data serves as a definitive, actionable baseline ahead of upcoming UN climate summits. Because every fraction of a degree of warming correlates with quantifiable increases in extreme weather events, heatwaves, and ocean acidification, the WMO argues that this forecast is a vital precision tool rather than a signal of defeat.[1][3]

By mapping exactly where and how fast the climate is shifting, these predictive models provide the exact empirical foundation required to optimize global adaptation strategies. The clarity of the 2025–2029 forecast empowers governments to update their Nationally Determined Contributions (NDCs) with eyes wide open, utilizing the best available science to navigate the critical years ahead.[2][3]