America's Strongest Hurricanes Were Tropical Storms Just Three Days Before US Strike, NHC Says

America's strongest hurricanes intensified significantly in the three days before they struck the U.S., illustrating the importance of having a hurricane plan together before a storm develops.

T​he 10 most intense U.S. hurricanes: Plotted on the map below are the tracks of the 10 strongest hurricanes to have struck the mainland U.S., by wind speed. As you can see, they span over 100 years from the most recent - Ian in 2022 - to the early 20th century - the 1919 Florida Keys hurricane.

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T-minus three days, or less: In a late April webinar, National Hurricane Center warning coordination meteorologist Robbie Berg noted each of these 10 most intense U.S. hurricanes were tropical storms just three days, or less, before they struck the U.S.

I​n the above map, you can see the locations where each of those hurricanes was a tropical storm only 72 hours or less away from its U.S. strike.

Why this happens: As the map shows, all 10 of these strongest U.S. hurricanes intensified in the Caribbean Sea, Gulf of Mexico or near the Bahamas.

T​hese homegrown hurricanes are more often a threat than longer-lived, Cape Verde hurricanes originating far in the eastern Atlantic Ocean, simply because they either form or intensify closer to the U.S.

T​hey do that because the Caribbean Sea and southern Gulf of Mexico usually have the most ample supply of warm, deep water, as the map below shows. If there are no other negative factors, warmer water leads to a stronger hurricane.

It also turns out, all those top 10 most intense U.S. hurricanes occurred either in August, September or early October. That's the peak of the hurricane season, when water is warmest and typically hostile wind shear and dry air are lower.

A couple of examples: The most egregious recent illustration of this was Hurricane Otis' rapid intensification before it clobbered Acapulco, Mexico, as the most intense Eastern Pacific hurricane landfall on record on Oct. 25, 2023.

I​n 2021, Ida was a tropical storm southwest of Jamaica on Aug. 26. Three days later, it made a Cat. 4 landfall in southeast Louisiana.

The 2024 Atlantic hurricane season is expected to be extremely active, including a higher threat of U.S. hurricane landfalls.

S​afety takeaways: While this isn't necessarily the case for all U.S. hurricanes, and there are certainly those that curl away and miss the mainland, 72 hours isn't as much time as it sounds to prepare.

This illustrates some important points about hurricane safety.

• Prepare for hurricane season before a storm forms. You may have less time to rush preparations to completion once the storm has already formed.
• K​now if you're in a hurricane evacuation zone, where you'll go and how you'll get there.
• D​uring hurricane season, pay close attention to the forecast, including here at weather.com, for the latest on any tropical storms or hurricanes, including those that could form and strengthen quickly.

M​ORE ON WEATHER.COM

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-​ Summer Outlook

Jonathan Erdman is a senior meteorologist at weather.com and has been covering national and international weather since 1996. His lifelong love of meteorology began with a close encounter with a tornado as a child in Wisconsin. He completed a Bachelor's degree in physics at the University of Wisconsin-Madison, then a Master's degree working with dual-polarization radar and lightning data at Colorado State University. Extreme and bizarre weather are his favorite topics. Reach out to him on X (formerly Twitter), Threads, Facebook and Bluesky.