Cooling La Niña could be back, but global temperatures set to rise: WMO

Latest data shared by the World Meteorological Organization (WMO) indicates a 55 per cent likelihood that sea surface temperatures in the equatorial Pacific will cool to La Niña levels from September to November.

About 90 per cent of the excess heat from global warming is stored in the ocean, making ocean heat content a critical indicator of climate change. 

“For October to December 2025, the probability of La Niña conditions slightly increases to about 60 per cent. There is little chance of El Niño developing during September to December,” WMO said in an update.

According to the UN agency, there is a smaller chance (45 per cent) that Pacific temperatures will stay as they have for the past six months, when neither the cooling La Niña nor its opposite number, the warming El Niño, caused unusual spikes or dips in sea surface temperatures.

Lifesaving insight

The UN agency’s forecast for the El Niño Southern Oscillation phenomenon is an important climate intelligence tool which could “save thousands of lives when used to guide preparedness and response actions”, insisted WMO Secretary-General, Celeste Saulo.

The information could also translate into millions of dollars of savings in agriculture, energy, health and transport, she said.

Important as La Niña and El Niño are in shaping our climate by altering ocean surface temperatures and impacting changes in winds, pressure and rainfall patterns, human-induced climate change is still “increasing global temperatures, exacerbating extreme weather, and impacting seasonal rainfall and temperature patterns”, WMO noted.

Each year of the past decade has been the top 10 warmest on record, the UN agency warned earlier this year, with 2024 the hottest yet, with “exceptional land and sea surface temperatures and ocean heat”.

Citing six international datasets, WMO said that global average surface temperature was 1.55 °C (34.79F) above the 1850-1900 average.

“Blazing temperatures in 2024 require trail-blazing climate action in 2025,” said UN Secretary-General Antóno Guterres at the time. “There’s still time to avoid the worst of climate catastrophe. But leaders must act – now,” he insisted.

Other key climate phenomena that influence global temperature include the North Atlantic Oscillation, the Arctic Oscillation and the Indian Ocean Dipole. Their impact on surface temperatures and rainfall are monitored by WMO and published in regular Global Seasonal Climate Updates (GSCU).

The latest Update indicates that for September to November, temperatures are expected to be above normal in much of the Northern hemisphere and large parts of the southern hemisphere.

Rainfall predictions are expected to be similar to those typically observed during a moderate La Niña, the WMO assessment noted.