For ship operators and insurers, this is more than just a scientific curiosity. When a tropical wave can strengthen from a faint swirl to a major hurricane in a couple of days, planning windows and the ability to mitigate their impact are dramatically reduced. Routes, port calls, and even crew schedules can hinge on how fast those changes unfold. As Mathew Dib (CMet, FRMetS), Duty Director of Marine Operations at Pole Star Global, explains, being armed with the appropriate data intelligence tools can help to cut through uncertainty and support faster, better-informed decisions for those at sea.
A season of contrasts
By late September this year, nine named storms had developed, with three becoming major hurricanes. Erin and Humberto both reached Category 5 strength over open water, while Gabrielle peaked as a Category 4. Even so, overall activity still lags behind the pre-season forecast many expected of around 14 to 19 storms.
During the early months of this season, from June through to August, the tropical Atlantic was smothered by dry, dusty air blowing west from the Sahara. This had the effect of limiting convection, stopping smaller systems from harnessing the moisture they needed to build into something more severe. Another factor at play within this was strong vertical wind shear, which was tearing storm cores apart before they could consolidate. In all, most systems fizzled or curved harmlessly into the open ocean and away from danger. Only Barry in Mexico and Chantal near the U.S. Southeast made meaningful landfall.
This disparity between forecasts and what played out at sea led some observers into a false sense of security, thinking the season might stay mild. Then, almost overnight, the pattern flipped dramatically. Three tropical cyclones – Humberto, Idalia and Jose – appeared within just eleven days, serving as a sharp reminder of how quickly a lull can give way to clustered, high impact activity.
Atmospheric drivers behind the shift
Several overlapping forces help explain the swing from periods of calm to sudden bursts of energy. The Madden–Julian Oscillation (MJO), which alternates between phases that promote or suppress convection, spent much of the summer in an unfavourable state for the Atlantic. When it shifted into a more active phase in September, this fed energy into developing systems, and storms followed quickly.
At roughly the same time, a developing La Niña began to relax upper-level winds across the basin. La Niña years often provide a calmer environment aloft, allowing cyclones to stay vertically aligned and intensify. Add sea-surface temperatures running abnormally warm at around one to two-and-a-half degrees above average, and the conditions for rapid intensification were suddenly present.
It’s also worth noting that the Saharan dust belt pulled northward as autumn approached. With less dry air and more humidity in the main development region, tropical waves finally found the ingredients they had been missing.
What the numbers tell us
By mid-September, the Accumulated Cyclone Energy (ACE) index was around 81, roughly 15 per cent below the long-term average of 95.
Nearly 90 per cent of that total came from just three storms: Erin, Gabrielle and Humberto.
That imbalance isn’t anything new, but it is a pattern that is becoming more familiar. Fewer storms are now responsible for most of each season’s total energy, suggesting that the Atlantic’s risk profile is concentrating into shorter, sharper peaks. For those at sea, this means that the danger period for shipping can be compressed into a few volatile weeks rather than stretched across the summer.
Strong systems appearing back-to-back in short spaces of time create their own headaches and ripple effects too. Ports face increased congestion, cargo is rerouted or delayed, and insurance for vessels operating within these windows and periods of volatility swing violently too, often persisting long after the weather clears. As a result of this for operators across the Caribbean and Gulf, flexibility and near-real-time awareness have become every bit as critical as long-range forecasting.
The outlook for the rest of the season
Although the first half of the season was subdued, this doesn’t rule out the possibility of a busier close. Exceptionally warm water, an ongoing La Niña and a thinning of Saharan dust all favour the development toward greater activity. With the MJO still in a favourable phase too, there’s a decent chance of multiple long-track storms emerging from African tropical waves through October and potentially into November too.
Even if the final storm tally stays below the high end of early forecasts, the risks are far from over. Having two Category 5 hurricanes in consecutive years is unusual, but it points to just how much heat energy the Atlantic now stores. When that warmth coincides with weaker wind shear, storms can strengthen alarmingly fast, sometimes within just a day or two.
Simply put, the busiest stretch of the season is still likely to come. History tells us that September and October are typically the most active months, and late-season systems have often been among the most destructive. For example, Hurricane Sandy (2012) and Hurricane Wilma (2005) together caused nearly $84 billion in U.S. damages, while Hurricane Mitch (1998) led to more than 11,000 fatalities and billions more in losses across Central America. On that basis, it would be premature to assume the Atlantic hurricane season has given all it has to offer. Conditions remain primed for surprises before the year closes. The Pacific, by contrast, appears calmer for now, though of course not free from risk. For operators, the task is rarely about avoiding storms altogether, but about maintaining continuity when they inevitably appear.
Adapting to the new rhythm
All of this season’s uneven pacing points to a growing realisation that predictability is falling. Factors such as the heat of the oceans, shifting patterns within the atmosphere, and unstable climate oscillations are working together to make hurricane behaviour more erratic and, as a consequence, inherently more difficult to predict accurately.
For those operating in the maritime industry, preparedness can no longer be an annual exercise built around seasonal forecasts.
It has to be a continuous process, and one driven and supported by live data, cross-ocean visibility, and the ability to make operational decisions in real time.
Operators must go beyond automated forecasts and seek tailored guidance, taking into account operational constraints such as a vessel’s limits regarding sea state or other navigational factors. That human element is essential to interpret forecasts and discuss them in context, highlighting potential risks, suggesting adjustments to route or speed, or even recommending delays when conditions warrant. Such dynamic, situation-specific analysis enables decision-makers to respond proactively rather than reactively, maintaining operational safety and efficiency even when conditions are shifting unexpectedly.
The goal isn’t to predict every storm with absolute precision but to ensure that those at sea have access to real-time, relevant information, with /365 support, and structured insights that can inform immediate operational choices, enhancing vigilance, connectivity, and agility in the face of unpredictable weather.
For those at sea or managing fleets ashore, the advantage now lies in awareness, knowing sooner, acting faster, and adjusting before disruption takes hold.
Source: By Mathew Dib (CMet, FRMetS), Duty Director of Marine Operations at Pole Star Global
