Elevated hurricane risk for 2025 as a warm Atlantic and weak La Niña conditions align

Predicted conditions for the 2025 hurricane season include above average Atlantic sea surface temperatures and neutral to weak La Niña conditions in the Pacific. Historically, this combination has been associated with more active and damaging hurricane seasons.

Sea surface temperatures (SST) in the Main Development Region (MDR) and the El Niño–Southern Oscillation (ENSO) are two of the most important large-scale drivers of Atlantic hurricane activity. Warmer MDR SSTs provide more energy for storm formation and intensification, while ENSO influences atmospheric wind shear. During La Niña conditions (ENSO < -0.5) wind shear is reduced making the environment more favourable for hurricane development and intensification. Conversely during El Niño conditions (ENSO >0.5) wind shear is enhanced making the environment more hostile for hurricane development and intensification.

The plot shows 40 years of North Atlantic hurricane seasons plotted in ENSO–SST space where the larger pink bubbles have larger losses and small blue bubbles have low losses. The lower-right quadrant is characterized by cooler SSTs and predominantly El Niño conditions. This quadrant represents the lowest physical risk regime, notably with only one major loss year – 2018 (Michael, Florence).

The upper-left quadrant is characterized by warm SSTs and predominantly La Niña conditions. This thermodynamic setup is highly conducive to both tropical cyclone formation and intensification. The clustering of large loss years in this quadrant is striking, demonstrating a link between the physical parameters and the losses experienced.

For 2025, ENSO forecasts suggest values between -0.5 and 0.0, while SSTs in the Main Development Region are expected to be above average. Extreme SST anomalies are not anticipated, so likely not more than 0.5°C above average. This places the upcoming season in the high-risk quadrant.

Looking at just the losses in the yellow box, which bounds the ENSO and SST predictions, we see years such as 2005 (Katrina, Rita, Wilma), 2017 (Harvey, Irma, Maria), and 2008 (Ike, Gustav) – some of the most devastating hurricane seasons on record.

Although risk is elevated this season, and a high-loss outcome is more likely given the physical setup, being in the high-risk quadrant does not guarantee that 2025 will be a high-loss year.