In April, a rare triple-cyclone setup near the equator drove what one scientist called the strongest westerly wind burst in over 50 years. Here's the mechanism, and why it rhymes with 1997 and 2015.
Every strong El Niño needs a shove. The ocean can be primed (warm subsurface water stacked up in the western Pacific, waiting), but something in the atmosphere usually has to kick it loose. This spring, that shove arrived in an unusually dramatic form: three tropical cyclones, flanking the equator at nearly the same time, driving what may be the most powerful westerly wind burst in half a century. It's a big part of the reason the "very strong" odds for this El Niño roughly doubled between May and June. Here's how that actually works.
Normally, trade winds blow east to west across the equatorial Pacific, piling warm surface water up against Indonesia and the Philippines and holding the cold, nutrient-rich water close to South America. A westerly wind burst is a short, sharp reversal of that pattern: winds blow west to east instead, for anywhere from a few days to a few weeks, concentrated in the western equatorial Pacific.
That reversal does two things that matter enormously for El Niño. First, it directly pushes warm surface water eastward. Second, and more importantly for the physics, it launches a downwelling oceanic Kelvin wave: a slow-moving pulse that travels along the equator and deepens the thermocline (the boundary between warm surface water and the cold water below) as it crosses the Pacific over several weeks. Where that Kelvin wave arrives, the ocean surface warms. That warming weakens the trade winds further, which can trigger more westerly wind bursts, which launches more Kelvin waves: the self-reinforcing chain reaction known as the Bjerknes feedback, the engine at the center of every El Niño. Research has found that major El Niño events are typically preceded or reinforced by one or more significant westerly wind bursts.
Twin tropical cyclones straddling the equator (one north, one south) happen roughly once or twice a year and are a well-documented trigger for westerly wind bursts on their own; each storm's counterclockwise (Northern Hemisphere) or clockwise (Southern Hemisphere) rotation reinforces westerly flow between them. Triplets are a different story. In early-to-mid April, Tropical Cyclone Maila spun up near the Solomon Sea and briefly reached Category 4 strength before drifting toward Papua New Guinea; Cyclone Vaianu developed well to its southeast, approaching Category 3; and Typhoon Sinlaku formed in the Northern Hemisphere near Guam. All three were active at nearly the same time, flanking the equator on both sides, an unusual configuration that meteorologists described as rare.
SUNY Albany atmospheric scientist Paul Roundy, who tracks these events closely, put it plainly at the time: the burst was "likely to be the strongest in over 50 years, and probably in the last century." He added that given how confident the westerly wind forecasts were over the following two weeks, "the likelihood of this event [a stronger El Niño] failing must be small." NOAA's Nat Johnson, at the Geophysical Fluid Dynamics Laboratory, described his model's own output around the same time as projecting the second-strongest event since 1991: "only 1997 was comparable."
The 2026 setup isn't unprecedented in kind, only in degree. The same mechanism shows up at the doorstep of the two most-cited historical super El Niños:
None of this means 2026 is guaranteed to match 1997. Wind bursts are a trigger and an amplifier, not the whole story: the ocean's pre-existing heat content, the atmosphere's ongoing response through summer, and simple bad luck with the next few months' weather all still matter. But the pattern-matching here is real, not manufactured: this is one of the defining mechanisms observed before the strongest El Niño events in the modern record, alongside the pre-existing subsurface heat buildup and the ongoing atmospheric coupling that has to follow through summer for any of it to matter.
Westerly wind bursts are closely tied to the Madden-Julian Oscillation, the eastward-propagating envelope of tropical convection that we've written about before: MJO activity in Phases 6-7 (western Pacific) is a classic setup for exactly this kind of wind-burst trigger. If you want the deeper mechanics (Kelvin waves, the MJO's eight-phase cycle, how the Bjerknes feedback loop actually closes), that's covered in full in our teleconnections reference catalog, published today, which walks through this and the 29 other atmospheric and oceanic patterns that interact with ENSO.
The short version for anyone just watching the headlines: this El Niño didn't just get lucky with warm water. It got hit, three times in a row, by exactly the kind of atmospheric push that has preceded the biggest events in the modern record. That's a real reason for the raised odds, not hype.