Global Seasonal Climate Update for July-August-September 2026

Outlook for Oceanic Drivers for the Next Season

For the July–September 2026 (JAS 2026) season, the multi-model ensemble (MME) indicates a rapid development into a strong El Niño event. By JAS 2026, the MME is forecast to reach approximately 2.0°C for the seasonal average. The intensification trajectory maintains an upward trend throughout the boreal autumn. Spread among the individual forecast systems is generally narrow during JAS 2026, indicating high forecast confidence.

The Indian Ocean is also forecast to experience development of the positive IOD phase, with the JAS 2026 seasonal mean value of 0.6°C. Meanwhile, the equatorial Atlantic basin is expected to remain generally warm; SSTs in both the North and South Tropical Atlantic are predicted to stay slightly above normal.

Surface Temperature Outlook for the Next Season

The MME forecasts project a nearly universal global dominance for enhancement in probabilities for above-normal temperatures over landmasses. This is especially pronounced throughout the globe between 60°S and 60°N, where a large increase in probabilities for above-normal temperature is reinforced by high model consistency.

In the Northern Hemisphere, a large increase in probabilities for above-normal temperatures spans across northern Africa, southern Europe, the Arabian Peninsula, the Indian Subcontinent, eastern Asia, and western parts of North America below 60°N, as well as Central America and the Caribbean. Model consistency across these regions is moderate to strong. Conversely, a weaker enhancement in probabilities of above-normal temperatures is indicated north of 45°N over Asia, and across the northwestern and eastern regions of North America.

In the Southern Hemisphere, a strong enhancement in probabilities for above-normal temperatures is centered over southern Africa, between the equator and 30°S over South America, and across New Zealand, supported by strong model consistency. Over Australia, the signal is split: a moderate increase in the probability for above-normal temperature is forecast for the southern parts of the continent, whereas a much weaker signal is present in northern regions.

In the tropics, a large increase in probabilities for above-normal temperatures covers equatorial Africa, northern South America, and the northern part of the Maritime Continent. Over the oceans, the equatorial Pacific reflects a heavily structured footprint of the rapidly intensifying El Niño event. Extreme probabilities (exceeding 80%) for above-normal SSTs dominate the equatorial Pacific east of the Date Line, where the core of the warm region displays maximum model consistency.

A widespread tendency for above-normal temperatures also covers the Indian Ocean and the tropical Atlantic. In contrast, a persistent horseshoe-like pattern of below- to near-normal temperature probabilities is predicted across the North Atlantic, straddling the probability for warmer anomalies along 30°N.

Rainfall Outlook for the Next Season

For the JAS 2026 season, MME forecasts project well structured, large tilts in rainfall probabilities, exhibiting a classic, strong atmospheric response to Pacific El Niño. The most dominant feature of the JAS 2026 outlook is a strong enhancement in the probability for above-normal rainfall stretching across the central and eastern equatorial Pacific east of the Date Line, backed by strong model consistency. This core convective signal is flanked by an extensive region of below-normal rainfall probabilities. This broad dry signal encompasses widespread marine zones, manifesting as strong enhancements in the probability for below-normal rainfall over both the tropical Indian Ocean and the equatorial Atlantic Ocean.

The Indian Subcontinent features an enhancement in the probability for below-normal rainfall, exhibiting high model consistency across the region. Over Australia, there is an enhancement in the probability for below-normal rainfall dominating over most of the continent. Across equatorial Africa, the probabilistic signals display a prominent east-west contrast. Land areas bordering the northern Gulf of Guinea exhibit an enhanced probability for above-normal rainfall. Conversely, moving eastward, the Greater Horn of Africa shows a distinct, enhanced probability for below-normal rainfall. Flanking this equatorial belt, a weak enhancement in the probability for above-normal rainfall is indicated over both the far northern and southern parts of Africa.

There is an enhancement in the probability for below-normal rainfall covering the southern parts of Central America and the Caribbean. To its north, there is an enhancement in the probability for above-normal rainfall over the western parts of North America below 45°N. In South America, a robust dry signal is centered over the northwest, with an enhancement in the probability for below-normal rainfall continuing steadily along the northern coastal areas to the east.

Across Europe, the MME forecasts a latitudinal split. An enhancement in the probability for above-normal rainfall covers the southern parts of Europe, whereas an enhanced probability for below-normal rainfall is predicted across northern Europe. The consistency is low to moderate.

Figure 1. Probabilistic forecasts of surface air temperature and precipitation for the season July-September 2026. The tercile category with the highest forecast probability is indicated by shaded areas. The most likely category for below-normal, above-normal, and near-normal is depicted in blue, red, and grey shadings respectively for temperature, and orange, green and grey shadings respectively for precipitation. White areas indicate equal chances for all categories in both cases. The baseline period is 1993–2009.

WMO LC-SPMME