When will El Niño end and what weather patterns will it bring for hurricane season 2024?
With hurricane season just around the corner, conversations about the shift to the La Niña phase of the El Niño Southern Oscillation (ENSO) weather patterns are causing a stir.
As of Mar. 14, the National Oceanic and Atmospheric Administration (NOAA) forecast a 62% chance of ENSO patterns drifting into a La Niña phase for summer 2024.
ENSO affects weather conditions across the globe. When La Niña conditions appear, drier weather tends to dominate in the southern U.S. while the Pacific Northwest and Canada tend to be colder and wetter. The current phase of ENSO also affects weather patterns over the Gulf of Mexico, Caribbean Sea, and northern Atlantic Ocean, creating optimal conditions for hurricane development and potentially leading to a more severe hurricane season.
However, at the time of NOAA’s announcement, there was an ongoing El Niño advisory, which means that El Niño conditions are present and expected to continue. In January, sea surface temperatures (SSTs) were above average in most of the Pacific, but they were dropping from the highs recorded in 2023. At the peak of El Niño, SSTs were the fifth-highest recorded since 1950, underscoring the strength of the most recent El Niño phase.
Historically, there is a tendency for La Niña to follow strong El Niño events.
What Could This Mean for Hurricane Season 2024
Between late summer 2020 and summer 2023, the ENSO cycle was in a strong La Niña phase, which aided in hurricane formation in the Atlantic.
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During a La Niña phase, the vertical wind shear over the North Atlantic Ocean basin can decrease. Vertical wind shear, or the change in wind speed or direction in conjunction with altitude, deters hurricanes from developing or intensifying. When wind shear decreases, it is easier for hurricanes to strengthen into major hurricanes.
The last La Niña phase coincided with storms such as Hurricane Ian, Hurricane Nicole, and Hurricane Ida.
Sea surface temperatures also influence hurricane development, with warmer waters in the Gulf of Mexico and the Atlantic leading to larger, more powerful storms. North Atlantic Ocean SSTs are expected to remain high throughout 2024, potentially setting records that were shattered only just last year.
Nevertheless, before La Niña conditions are present, NOAA expects a transition from El Niño to ENSO-neutral. In March, they noted that the likelihood of this transition between phases is 83%.
The severity of the 2024 hurricane season depends on several factors like SSTs, the amount of heat at depth within the ocean — also known as ocean heat content — and the consistency of vertical wind shear in the North Atlantic Ocean. While NOAA has yet to release their seasonal forecast — the forecast is expected in mid- to late May, it would be surprising to see near- or below-average activity given the long-term SST patterns and high probability of a shift to La Niña.
When Will El Niño End in 2024?
At this point, NOAA has stated that the current El Niño event has passed its peak although its impacts on temperatures and precipitation can linger through April.
While weather patterns can be modeled, the exact timing of the transition between ENSO phases remains uncertain. Nevertheless, since 1950, over half of the El Niño events were followed by a transition to La Niña, so it is reasonable to expect a similar outcome in 2024.
Hurricanes are inevitable. However, there are opportunities for people and communities to ensure resilience by knowing their risk to accelerate their recovery. For those living in areas of the U.S. that are vulnerable to hurricane damage, this transition between ENSO phases should signal the need for preparedness.
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