As the 2026 Atlantic hurricane season approaches, a growing body of peer-reviewed research shows that tropical cyclones worldwide have been losing forward speed for decades, and that warming ocean temperatures are making those slower storms more intense and wetter. For the Caribbean, a region where millions of people live on steep, flood-prone terrain just a few feet above sea level, the combination is especially dangerous.
What the research shows
The foundational finding comes from a 2018 study published in Nature by James Kossin, a former NOAA scientist. Analyzing global best-track cyclone records from 1949 to 2016, Kossin found that tropical-cyclone translation speed dropped by about 10 percent over that 67-year window. The slowdown was not uniform across every ocean basin, but it appeared in multiple regions, including the North Atlantic waters that feed Caribbean hurricanes.
The physics behind the danger are straightforward: a storm that moves at 8 mph dumps roughly twice as much rain on a given location as the same storm moving at 16 mph. Slower translation means longer exposure to destructive winds, higher storm-surge pileup, and far greater rainfall totals. For communities in narrow valleys or on saturated hillsides, those extra hours of rain can be the difference between manageable flooding and disaster.
A separate line of research connects rising sea surface temperatures directly to storm strength. A 2024 study in Communications Earth & Environment examined how marine heatwaves, episodic spikes in ocean temperature that have grown more frequent and intense, affect cyclone behavior. The researchers found that storms passing over these warm anomalies draw additional thermal energy from the ocean, boosting wind speeds and moisture uptake. When a slow-moving cyclone sits over one of these hot patches, it feeds on that energy for a longer period, amplifying both its intensity and its rainfall potential.
The economic consequences are already visible. A study published in Science Advances and reported by the Associated Press found that marine heatwaves are associated with a higher proportion of billion-dollar disaster outcomes and more frequent rapid intensification among landfalling cyclones. However, the study identifies a statistical association rather than direct causation; NOAA’s disaster cost data captures total economic losses that also reflect population growth, construction in flood-prone areas, and rising property values. NOAA’s National Centers for Environmental Information, which maintains an inflation-adjusted record of billion-dollar U.S. weather disasters, consistently ranks tropical cyclones among the costliest event types.
Why the Caribbean is particularly exposed
Caribbean islands sit in some of the fastest-warming waters on the planet. Geography compounds the problem. Many Caribbean nations are small, mountainous, and densely settled along narrow coastal strips. Drainage infrastructure in cities across the region was not designed for the kind of prolonged, extreme rainfall that slow-moving storms deliver. When storms crawl across small islands at single-digit forward speeds, the result is often devastating water damage even when peak winds remain below major-hurricane thresholds.
What remains uncertain
The 10 percent slowdown figure spans nearly seven decades, and not every scientist is convinced the trend is equally strong in every basin or every era. A 2019 analysis by James Lanzante, published in Nature, questioned the robustness of the slowdown signal in certain basins, arguing that data-quality issues in the early decades of the best-track record could account for part of the apparent trend. Early decades relied on sparse ship observations and aircraft reconnaissance, while later years benefited from continuous satellite coverage. That evolution in data quality can introduce biases into long-term trend estimates. Kossin and others have attempted to correct for these issues, but the debate underscores that some uncertainty persists about how much of the apparent slowdown reflects real atmospheric change versus improved detection of weaker, shorter-lived storms.
Projections specific to the Caribbean basin after 2016 remain limited in the peer-reviewed literature. The global datasets provide strong evidence of a broad trend, but isolating how much of the slowdown applies to any single sub-basin requires finer-grained analysis that not all studies have attempted. Researchers are still working to determine whether future storms in this region are more likely to stall, re-curve, or shift their typical tracks, and how those changes will interact with increasingly frequent marine heatwaves.
There is also the question of how much rising disaster costs reflect storm behavior versus human choices. Population growth along Caribbean coastlines, construction in flood-prone areas, and rising property values all inflate damage totals independent of any change in storm characteristics. Disentangling the climate signal from the development signal is an active area of research, not a settled question.
What it means as the 2026 hurricane season approaches
In the spring of 2026, Caribbean sea surface temperatures remain above the long-term average, according to NOAA monitoring data. Whether that translates into another active season depends on a range of atmospheric factors, including wind shear patterns and the state of the El Nino-Southern Oscillation cycle. But the underlying trend is clear: the ocean is warmer than it used to be, and warmer oceans favor stronger, wetter storms.
For residents and emergency managers across the Caribbean, the practical takeaway from this research is blunt. A storm’s wind category is not a reliable proxy for its flood risk. A tropical storm that barely moves can cause more water damage than a fast-moving Category 3 hurricane. Forecast discussions that include expected forward speed and rainfall totals deserve at least as much attention as the headline wind number.
Communities that have historically prepared mainly for wind damage may need to rethink building codes, drainage infrastructure, and evacuation triggers. The research collectively points in one direction: warmer Caribbean waters are creating conditions where storms intensify faster and, in many cases, move more slowly. That combination concentrates rainfall over smaller areas for longer periods, turning water, not wind, into the dominant threat from Caribbean tropical cyclones.
More from Morning Overview
*This article was researched with the help of AI, with human editors creating the final content.
