Global Heat Signals Rise: Oceans and Land Face Warmer May–July 2025 Outlook

The forecast for the May–July 2025 season suggests a transition toward a neutral El Niño–Southern Oscillation (ENSO) state.

Overview: Persisting Warmth Despite Waning La Niña Indicators

As the world transitions from early-year weather patterns into the boreal summer months of May through July 2025, global sea surface temperatures (SSTs) continue to reflect widespread anomalous warmth. The seasonal mean from January to March 2025 revealed predominantly above-average SST anomalies across much of the globe's oceans, with one notable exception—the equatorial central Pacific near the Dateline. Here, weak below-average SST anomalies persisted, hinting at residual effects of a decaying La Niña pattern.

However, SST anomalies in the eastern Pacific Ocean—particularly the Niño 1+2 and Niño 3 regions—remained above average, while those in the central Pacific (Niño 3.4 and Niño 4) hovered near or slightly above average. These conditions presented a somewhat mixed picture, consistent with a weak La Niña, though indicators increasingly pointed toward an approaching ENSO-neutral phase.

ENSO Outlook: Transition to Neutral Conditions Expected

The forecast for the May–July 2025 season suggests a transition toward a neutral El Niño–Southern Oscillation (ENSO) state. SST anomalies in the Niño 3.4 and Niño 3 regions, which are key indicators of ENSO phase transitions, are projected to remain close to climatological averages. Similarly, the Niño 4 region farther west is expected to see a decline in SST anomalies, reinforcing a shift away from the weak La Niña state previously observed.

Atmospheric conditions, however, may continue to exhibit patterns similar to a weak La Niña, particularly regarding rainfall distribution, despite the absence of strong supporting oceanic signals.

Indian and Atlantic Ocean Trends

The Indian Ocean Dipole (IOD) index for the same upcoming period is forecast to dip slightly into negative values. This subtle shift could contribute to moisture variations and regional climate disruptions, particularly around the Indian subcontinent and surrounding regions.

In the Atlantic basin, both the North Tropical Atlantic (NTA) and South Tropical Atlantic (STA) are expected to retain their above-average SST anomalies. This ongoing oceanic warmth in the equatorial Atlantic, sustained over the past year, is anticipated to influence regional atmospheric convection and rainfall variability across the Atlantic rim and adjacent land areas.

Land Surface Temperature Outlook: Broad Global Warming Footprint

Echoing the persistent ocean warmth, the climate forecast indicates that above-normal land temperatures are likely to dominate the May–July 2025 season across most global regions. The most pronounced increases in temperature probabilities are projected over:

• Arabian Peninsula to Eastern Asia

• The Maritime Continent and adjacent Pacific areas

• North and South America (above 20°N and northward into the Caribbean, Central America, and parts of the U.S.)

• Europe and Northern Africa

• New Zealand

In contrast, slightly reduced enhancements in temperature probabilities are expected across:

• Indian Subcontinent

• Southern Africa

• North-eastern Australia

• Southern parts of South America

These distinctions suggest that while warming will be widespread, some regions may be less affected due to localized influences or atmospheric variability.

Rainfall Projections: ENSO-Neutral, La Niña-Like Impacts

Even as oceanic ENSO indicators lean neutral, predicted rainfall distributions continue to reflect patterns reminiscent of a weak La Niña. Specifically:

• Below-normal rainfall is forecast between 150°E and the Dateline along the equatorial Pacific, a classic La Niña feature. This dry anomaly is expected to extend toward:

  • Western coasts of Central America

  • Southwestern North America

  • Equatorial Atlantic and northeast South America

  • Southeastern Pacific and the coast of South America near 30°S

  • Eastern Europe and western Central Asia

• Above-normal rainfall probabilities are forecast in regions such as:

  • Indian subcontinent

  • Eastern Asia

  • The Maritime Continent

  • Equatorial Africa (extending to 20°N)

  • Northwest South America

  • A belt along 60°S in the southern Pacific Ocean

Meanwhile, large landmasses including much of Australia, northeastern North America, eastern South America, and northern Asia show no strong signal, indicating a possible mix of near-normal conditions and high forecast uncertainty.

Conclusions and Implications

The climate outlook for May through July 2025 underscores the growing influence of neutral ENSO conditions, despite lingering atmospheric traits from the departing La Niña. The dominance of widespread oceanic warmth—especially in the Atlantic and Indian Oceans—signals the potential for continued global heat stress and rainfall variability.

Stakeholders in agriculture, disaster preparedness, water resource management, and public health should consider these projections in planning for seasonal anomalies. While not extreme, the subtle shifts in SST and rainfall patterns can have disproportionate impacts on food production, wildfire risk, and disease dynamics—particularly in vulnerable regions with limited adaptive capacity.