GENEVA, Switzerland (AFP) —  El Nino is here and will quickly develop into a strong event between July and September, fuelling the likelihood of extreme weather, the United Nations’ climate agency warned Friday.

The World Meteorological Organization (WMO) said the climate phenomenon would rapidly gain strength, as it warned countries to brace for impact.

El Nino warms surface temperatures in the central and eastern equatorial Pacific Ocean, bringing worldwide changes in winds, pressure and rainfall patterns.

It typically takes place every two to seven years and lasts around nine to 12 months.

Conditions oscillate between El Nino and its opposite La Nina, with neutral conditions in between.

The WMO’s monthly Global Seasonal Climate Update points towards “a rapid development into a strong El Nino event during July-September”.

The UN agency classifies El Nino events as weak, moderate, strong or very strong, meaning it is set to reach the third-highest level out of four.

“El Nino conditions have developed in the tropical Pacific and are forecast to strengthen rapidly over the coming months, increasing the likelihood of… extreme weather events in many parts of the world,” the WMO said.

WMO climate scientist Alvaro Silva told a press conference that since last month, “we have much more confidence that strong El Nino conditions are developing in the equatorial Pacific”.

He said the WMO may issue an update in the coming months, “for example, if we have forecasts suggesting this will be a really strong El Nino”.

The Geneva-based agency said forecasts produced by global climate centres, using different models, indicate a consistent and significant warming of ocean temperatures across the central and eastern equatorial Pacific.

“Seasonal-average sea-surface temperature anomalies expected to exceed 2C in key monitoring regions,” it said.

“El Nino is expected to continue strengthening during the Northern Hemisphere autumn, with its influence extending across many regions of the globe.”

The last El Nino contributed to making 2023 the second-hottest year on record and 2024 the all-time high at around 1.55C  above the 1850-1900 pre-industrial average.

While El Nino usually peaks between November and February, the resulting spike in temperatures typically comes later.

“The impacts of El Nino will be felt in different regions until the end of the year and beyond, also during 2027,” underlined Silva.

The WMO said it was stepping up early warning support to help guide preparedness, especially in climate-sensitive sectors like agriculture and health.

Such moves “are vital to save lives and cushion the impact on our economies and our communities”, said WMO chief Celeste Saulo.

“El Nino conditions are already under way and are forecast to strengthen rapidly into a strong event,” she said.

“This will intensify the chances of drought and heavy rainfall and the risk of heatwaves on land and marine heatwaves in many regions.”

The update predicts an overwhelming likelihood of above-average temperatures across most land areas between 60 degrees south and 60 degrees north — covering nearly all populated areas outside the polar regions.

And the July to September rainfall outlook is consistent with a strengthening El Nino, with above-normal rainfall forecast in areas including the southwestern United States, and below normal forecast across the Indian subcontinent and much of Australia.

The WMO says there is no evidence that climate change increases the frequency or intensity of El Nino events.

However, the agency believes it can amplify the associated effects, because a warmer ocean and atmosphere increase the availability of energy and moisture for extreme weather events, such as heatwaves and heavy rainfall.

During the northern hemisphere summer, warm waters associated with El Nino can fuel hurricanes in the central and eastern Pacific, while hindering their development in the Atlantic Ocean.

On Thursday, Peru declared a 60-day state of emergency in 800 of its 1,800 municipalities, due to the “imminent danger” of heavy rains linked to El Nino.

More than 9.3 million people in Peru were warned of a very high risk from flooding and landslides.