El Niño and Hurricane formation

 A strong El Niño acts like a massive atmospheric spoiler for the tropical Atlantic, particularly across the Main Development Region (MDR)—the stretch of ocean between West Africa and the Caribbean where most major hurricanes form.

The primary mechanism driving this is a dramatic increase in vertical wind shear (the change in wind speed and direction at different altitudes). Here is exactly how it unfolds:

The Atmospheric Pipeline

When a strong El Niño develops, the waters of the central and eastern tropical Pacific become exceptionally warm. This intense oceanic heat triggers massive, persistent thunderstorms over the Pacific.

As these storms pump warm air high into the upper troposphere (around 30,000 to 40,000 feet), it alters global air currents via teleconnections (atmospheric domino effects). This creates a powerful stream of upper-level westerly winds that race eastward across the Caribbean and directly into the Atlantic MDR.

     Wind sheer anomalies during El Niño 

Why This Tears Hurricanes Apart

To understand why this suppresses tropical activity, look at the conflict between the upper and lower atmosphere in the MDR during an El Niño: At the Surface: The prevailing winds are the low-level easterly trade winds, blowing from east to west (Africa toward the Americas). In the Upper Atmosphere: El Niño introduces powerful, anomalous westerly winds blowing from west to east.

Because the bottom layer of the atmosphere is moving west while the top layer is rushing east, any developing tropical disturbance gets caught in a violent tug-of-war. Hurricanes require a calm, vertically aligned column to chimney warm air upward and intensify. High vertical wind shear tilts this core, separating the low-level circulation from the upper-level heat source, effectively tearing the storms apart before they can organize. Even if ocean temperatures in the Atlantic MDR are warm enough to fuel a storm, the sheer mechanical force of these conflicting winds usually keeps a lid on the hurricane season.

We should not expect an above average season in 2026 due to these factors.

Written 26th June 2026

Author -David I Birch