Looking ahead to Hurricane Season 2025

The first round of hurricane-season predictions is out. The buzz has been muted because they are all relatively tame compared to recent years. But I thought a post was in order to explain what we think we know and what we definitely don't know.

The key issue to understand is called forcing. If the whole tropical Atlantic from Africa to Florida is extra warm, the number of storms and especially the number of hurricanes is "forced" higher by the extra energy in the water. If the long strip of water along the equator south of Hawaii is extra warm, the numbers are "forced" lower because storm-shearing, hostile upper winds across the Atlantic hurricane belt are associated with that condition. We call that scenario an El Niño.

Other macro factors can "force" the season in one direction or the other as well.

Well, this year, the forcing picture is murky. The tropical Atlantic between the Caribbean islands and Africa is only slightly warmer than the long-term average and significantly cooler than the last couple of years. The Caribbean and the Gulf are very warm, however, and other parts of the ocean are extra warm as well. In this scenario, disturbances might be less likely to intensify quickly over the tropical Atlantic, but if they make it to the Caribbean or Gulf, the energy boost should still be there.

In the Pacific, the water temperature in the strip of ocean of interest is forecast to be near normal to slightly cool. The key point is that no significant forcing is expected from that quarter for at least a good part of the hurricane season.

The net-net is the forcing from these macro factors looks wimpy at best, with the exception of the elevated heat content in the Caribbean and Gulf. That's why you see forecasts for the number of named storms this year under 20.

Colorado State University, where Dr. Bill Gray pioneered hurricane-season forecasting in 1984, is forecasting 17 named storms and 9 hurricanes, with 4 reaching Cat  3 or higher. An official "average" season has 14, 7, and 3. But those numbers are a bit misleading.

The National Weather Service derives the average from the 30 years between 1991 to 2020. Well, in the 90s, we didn't have the high-resolution satellites and many other data sources we have today, so it's likely some storms were missed. This means the average of 14 named storms is likely 1 or 2 low. (The 14 is rounded down from an arithmetic average of 14.4, so it's only a slight fraction below rounding to 15 to start with. So think of 15 or 16 as an appropriate modern average.)

The consensus of the early-season forecasts from multiple agencies is in line with the CSU prediction – just slightly above the average numbers.

With no strong forcing, however, unforecastable factors can have an outsized effect. The African monsoon—the weather pattern that generates disturbances over West Africa that become tropical disturbances—could kick into an extra-active mode. Or the general weather pattern could randomly become extra conducive for storms to develop, much the way it was extra hostile during August and into September last year. Without forcing to nudge things one way or the other, randomness can take over.

In the end, none of this changes how we should think about hurricane season. In 1990, I came up with this tagline for our annual hurricane special:  "Living along the coast means living with hurricanes, and there is nothing to do but be prepared. Ready, Set, Hurricane!"

That's still true, of course, but a preparation mindset is not only required along the coast. As we dramatically learned last year in the mountain communities of North Carolina and Tennessee and in Vermont in 2011, hurricanes have a wide reach.

Everyone within striking distance of the hurricane coast has some vulnerability. Now is the time to learn your area's weather history and susceptibility to dramatic impacts from tropical systems.