August and Everything After: Hurricane Watch Weekly Column for July 30th
A quiet Atlantic offers a chance to look ahead to August hurricane history, when U.S. hurricane risks historically accelerate.
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August arrives with a whiff of impending calamity. Fourth-graders who have eschewed summer reading in favor of Minecraft must hastily identify the setting and main characters of The Giver by Lois Lowry. Miami Dolphins fans attempt to stay positive while knowing yet another seven-to-nine-win season lies ahead. Many are unprepared for the existential agita of International Clown Week, which feels like a gratuitous quantity of time in which to celebrate the clowning arts. Welcome to August, the worst month of the year.
Fortunately, this August will begin with minimal clowning from the Atlantic, Gulf, or Caribbean. A couple of tropical waves are struggling across the Eastern Atlantic, staggered by dry air and a stable tropical atmosphere. By the middle of next week, it’s worth keeping an eye on the area between Florida, the Carolinas, and Bermuda, where one such wave may interact with a stalled-out cold front. But overall, I don’t see significant tropical threats to the U.S. in the first third of August.
That frees up bandwidth for a third entry in my six-part guided tour of hurricane season. (Expect the second half of WeatherTiger’s updated 2025 seasonal outlook next week.) Last year, I looked at the June and July preambles to the peak season; today, I’m diving into the hurricane history of August, a month in which the heat index, prospect of serious tropical threats, and even C+C Music Factory all are gonna make you sweat.
By the numbers: A hoary chestnut of nautical hurricane climatology first published in the 19th Century avers that in August, “look out you must.” Stilted mnemonics aside, August truly is the first month of hurricane season to encompass a sizable chunk of historical storm activity, accounting for about 20% of total Atlantic and 25% of continental U.S. tropical activity by Accumulated Cyclone Energy. That translates to typical counts of two to four named storms, one or two hurricanes, and nearly often as not, the first major hurricane of the year during August.
This late summer acceleration is due to the slender window in which favorable ocean, mid-level humidity, and shear conditions for development in the Tropical Atlantic overlap. Early in hurricane season, shear is typically lower, while sea surface temperatures and moisture lag; those latter two factors tend to improve dramatically over the course of August. As such, the final third of the month has recorded an equal number of developing storms as the first two-thirds over the past 125 years.
Where do they come from? As previously discussed, I’m a proponent of Three-Season Theory (Truchelut 2025), the idea that Atlantic “hurricane season” is comprised of three distinct flavors of storm development in time and space that don’t have a ton to do with each other. (This is not to be confused with Hybrid Theory [Bennington et al., 2000].) By August, we’re solidly into season #2, the platonic ideal of hurricane season, in which the main impetus for developing storms are tropical waves. These waves, actually cyclonic turning in low-level tropical trade winds, roll off the African coast and move west throughout the summer and fall. For the reasons above, they have the best chance of intensifying into hurricanes in August and September. Tropical organization most often occurs east of the Lesser Antilles, but waves that bide their time can also form later as they reach the Caribbean or Gulf. The western half of the Atlantic Basin is by far where major hurricane development is most commonplace.
Where are they going? Like a ramp into troubled water, August marks the transition between the tropical skirmishing of the first third of hurricane season, and the peak two months of U.S. risk between mid-August and mid-October. The rate of continental U.S. Category 3, 4, and 5 hurricane landfalls quadruples between the first and last ten days of the month, all while heckish heat and sauna humidity continues unabated in the Southeast. Like I said, worst month.
Early in August, the Central and Western Gulf Coast are the clear hotspot for continental U.S. hurricane landfalls. The historical tilt towards Mississippi, Louisiana and Texas strikes continues in late August, joined by a notable increase in the frequency of South Florida and Carolina coast landfalls from the east and southeast. The historical chances of at least one August named storm or hurricane landfall in the continental U.S. are about 60% and 40%, respectively, so “look out you must” isn’t that misguided as aphorisms go. Notch one for ancient mariners and their “rimes.”
Heavy hitters and worst-case scenarios: How bad can it get in August? As bad as the Atlantic hurricane season has to offer. August holds the crown for the month with the most continental U.S. Category 5 landfalls at two: Camille in 1969 and Andrew in 1992. Historically, there have been about 30 August U.S. major hurricane landfalls in the last 175 years, with a clear preference for these most powerful storms to strike the western half of the Gulf. Unfortunately, amongst these are the top two costliest hurricanes of all-time, 2005’s Katrina and 2017’s Harvey. Katrina, which registered nearly a quarter-trillion dollars in normalized damages, is also the deadliest continental U.S. August landfall on record, tallying around 1,500 lives lost.
What it means: Not to minimize the formidable threat posed by August storms in and of themselves, but how much Accumulated Cyclone Energy accrues over the month has predictive power for hurricane activity deeper into crunch time. If the environmental conditions in the Tropical Atlantic are conducive for generating big dogs in August, those favorable factors will likely persist into September and keep things percolating. Due to cycles of the Madden-Julian Oscillation, high activity at the very beginning and end of August may be particularly indicative of more hurricanes down the pike. However, as some recent underperforming Augusts have been followed by destructive remainders of the season (2018, 2022, 2024), this may be less true than it used to be.
Bottom line: In the medium term, August 2025 doesn’t look to kick off with any tropical distractions from the scramble to secure the 7 bespoke artisanal protractors, 96 small-batch, non-GMO glue sticks, and 155 sustainable forestry colored pencils our kids need to learn1. In the longer term, like the setting of The Giver, hurricane history shows the upcoming month can be downright dystopian. Before August slips away like a moment in time, it’s more likely than not that the U.S. will have to deal with at least some kind of tropical threat, probably in the final third of the month. Prepare your body, mind, and hurricane kit now for that reality, and keep watching the skies.
To say nothing of the TI-89, the timeless, immutable horseshoe crab of school supplies.
Watching September anxiously for my independent strong-willed (some say stubborn) mother-in-law who will turn 101 in September. We weathered Ian together. A serene 2023. Then, we left the day before Milton formed, after celebrating 100 while watching Helene. Please perform whatever voodoo you can to keep Englewood safe this year.
". . .that deep, sickening feeling of something terrible about to happen." -- The Giver, p. 1.