Analysis: El Niño may emerge in the tropical Pacific, but it can impact temperatures and rainfall patterns many thousands of kilometres away
As we entered the first week of summer here in Ireland, and a rather unsettled one at that, our news cycle on climate was dominated by one main headline: the El Niño. The World Meteorological Organisation (WMO) confirmed that there is an 80% likelihood of an El Niño event developing in the Pacific during the period from June to August, with models forecasting that this El Niño will be moderate to strong.
But what does this actually mean? What is El Niño and why is an event happening in the tropical Pacific Ocean generating such attention.
What is El Niño?
In a nutshell, El Niño relates to changing ocean temperatures and wind patterns in the tropical Pacific relative to normal. It occurs naturally in our climate systems and appears roughly every two to five years. Under normal circumstances, temperatures in the upper tropical Pacific Ocean are warmer in the west tropical Pacific (off the coast of Indonesia and Philippines) and colder in the east tropical Pacific (near Ecuador and Peru) and winds at the equator flow from east to west. El Niño is the reversal of this.
The winds weaken (and can be reversed in very strong El Niños) and the sea surface temperatures become much warmer than normal in the east tropical Pacific and become much cooler in the west tropical Pacific (see figure 1).
Why is El Niño so important?
El Niño is important because it also impacts the atmosphere above the tropical Pacific, and more importantly, this can impact other parts of the planet.
It known as a 'teleconnection' pattern. A teleconnection acts like a bridge in our atmosphere connecting seemingly distant locations (sometimes thousands of kilometres away), much like telecommunication systems or the butterfly effect. A system such as El Niño, which is based in only the tropical Pacific, can impact temperatures and rainfall patterns many thousands of kilometres away.
So how does it affect distant weather patterns? Imagine a pot of boiling water. When you place a pot of water onto a warmed stovetop, the water remains calm and steady at first. After a few minutes, the water warms, becomes lighter, starts to rise and bubbles appear. As more time passes, the water continues to heat and rise to the top, bubbling more rapidly until the pot starts to boil over. If you had a lid on the pot, at this point, it would be dancing vigorously as steam and energy are released.
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From RTÉ Radio 1's News at One, World Meterological Organisation Alvaro Silva on how this year's El Niño could be the strongest one in decades
This process is called convection, and the same process happens in the atmosphere. With a source of continuous heat (much like our stovetop), atmospheric convection (think of thunderstorms) is generated and all this heat and energy rises and eventually reaches a ‘lid’ and cannot rise any further. This region in our atmosphere is known as the tropopause and marks the edge of where our weather reaches; roughly the height at which airplanes fly.
This energy is then transported away from the tropical Pacific and moves either north or southward and impact the weather and climate far away from the Pacific for the following few months.
The impacts of El Niño
While no two El Niño events are the same, El Niño typically results in drier and warmer temperatures over southeast Asia and Australia and warmer temperatures over western Canada and North America, India and China. It also tends to result in wetter weather over southern South America, southern North America and across the Horn of Africa.
El Niño is also linked to changes in extreme weather events and can result in droughts in Indonesia, Australia, southern Africa, and India and flooding events from heavy rains in Ecuador and Peru. The El Niño also generally results in more hurricanes in the eastern Pacific but can reduce the number of hurricanes in the Atlantic.
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From RTÉ Radio 1's Drivetime, UK Met Office climate scientist Melissa Seabrook on how world heatwave records were broken in May 2026
This El Niño is getting particular attention because of is projected strength. Observations of ocean temperatures in the central-eastern tropical Pacific – the region used as the monitoring reference – are currently showing above average temperatures in both the upper ocean and deep within the ocean exceeding 6C above average.
These very warm temperatures hundreds of metres deep within the Pacific Ocean often lead to much warmer surface temperatures further fuelling a strong El Niño. However, it must be noted that there is still great uncertainty regarding how strong this El Niño will be, but there is relative certainty that El Niño is on the way.
What does the El Nino mean for Ireland?
While projections show an overall warming across the planet n response to El Niño, this does not mean glorious sunshine here in Ireland unfortunately. The influence on European weather from El Niño is not as clear as for countries such as South America, Australia and India as our weather is also heavily influenced by many other local processes unique in the North Atlantic.
Nonetheless some studies have shown an El Niño influence on colder winter temperatures in northeast Europe and less precipitation in northern Europe both of which includes Ireland. Therefore, we cannot be definitive in what to anticipate for Irish weather in the next few months because of El Niño, but as always, we can expect the unexpected.
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The views expressed here are those of the author and do not represent or reflect the views of RTÉ
