South Florida hurricanes: Where do they form, when do they strike?

Latest update on the tropics provided by Local 10 Hurricane Specialist and Storm Surge Expert Michael Lowry

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If you live in South Florida long enough, you’re bound to develop a theory on why and when a hurricane will strike.

When May is dry, look out. If a storm passes through the Hebert Box, we’re in trouble.

And these are just the theories from meteorologists (dry May courtesy of former Miami National Weather Service veteran Jim Lushine and the Hebert Box courtesy of NWS and NHC forecaster Paul Hebert). They’re fun and make for good fodder, but most theories are only a step removed from the proverbial groundhog or Old Farmer’s Almanac.

There are, however, a few rules of thumb about South Florida hurricanes that we can learn from looking back at the record books (for this discussion, South Florida is south of Lee County on the west coast and Palm Beach County on the east coast).

Going back to 1851, virtually all – 95 percent – of South Florida hurricanes occurred in August, September, and October. A hurricane did move through the Keys and Miami-Dade County in June of 1906, but this and a late July hurricane in 1933 are the only two hurricanes on record to impact South Florida prior to August.

What’s perhaps most intriguing about South Florida’s long hurricane history is more hurricanes have been observed in October than in any other month. Hurricanes are more common in October here because fall cold fronts more frequently make it into the central and southern Gulf of Mexico, often steering storms our way.

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The hurricanes that impact South Florida tend to form either in the deep tropics south of 20 degrees north latitude when east of the islands, south of 25 degrees latitude but north of the islands, or in the western Caribbean.

Nearly all hurricanes on record to strike South Florida in August and September formed north or east of the islands; of the 23 hurricanes on record to strike South Florida in October, all but two formed in the western Caribbean.

But even these general rules have their limits. An oddball storm that formed about 200 miles east of Bermuda on October 30, 1935, turned southward in November and struck Miami on Nov. 4. This was one of only two South Florida hurricanes to form north of Miami and is the only South Florida November hurricane landfall on record.

Looking back at South Florida’s hurricane history helps us to better understand the threats we face during hurricane season. June and July hurricanes in South Florida are rare. Early August hurricanes are uncommon (3 in 4 South Florida August hurricanes struck after Aug. 15).

The big months for hurricane impacts in South Florida are September and October, with October – especially middle to late October – turning late season hurricanes our direction.

I can’t tell you whether the dry weather we’ve had since mid-June means anything for the rest of hurricane season, but if you ask your neighbor, I’m certain they’ll have a theory, and I know it’ll be more entertaining than mine.


About the Author:

Michael Lowry is Local 10's Hurricane Specialist and Storm Surge Expert.