Just Because It's Fall Doesn't Mean We Shouldn't Pay Attention to the Tropics

Chris Dolce and Brian Donegan
Published: September 21,2016
When you think of October and November, perhaps the first thing that comes to mind are the leaves changing color and falling on your lawn. Or maybe you think of those first few cold fronts of the season bringing cooler, drier air to the country?
Certainly, these things do not make you think of tropical weather, but that doesn't mean you should let your guard down during the final third of the hurricane season.
(MAPS: Current Fall Foliage Reports)
The vast majority of hurricanes that have struck the U.S. since 1851 have done so prior to October. In fact, about 79 percent of U.S. hurricane strikes have occurred from June-September, according to NOAA.
But that means 21 percent of hurricanes have hit the U.S. between October and November, including some deadly and destructive ones late in the season. The overwhelming majority of those have occurred in October.

(NOAA)

Hazel, Kate, Wilma and Mitch are just a few of the names that pop into the minds of meteorologists when thinking about historic late-season hurricanes.
Most recently, Sandy in October 2012 caused devastation across the Northeast, from New Jersey to New York City and New England, and even brought heavy snow to parts of the Appalachian Mountains. Sandy technically made landfall in the U.S. as a non-tropical low pressure system, but was a hurricane just prior to that point very near the coast.
Sandy currently stands as the second-costliest hurricane in U.S. history with an estimated $67.6 billion in damage.

Season Slows Down Gradually

Since 1950, October has accounted for 17 percent of the named storms over the course of a season. October has seen more named storms since 1950 than June and July combined.

On average, two named storms and one hurricane form each year in the Atlantic Basin during October. As many as seven named storms (2005) and five hurricanes (2010) have formed in the month.
The pace of the season slows dramatically in November, with only one named storm forming every other year. Increasing winds aloft (wind shear) and stronger cold fronts plunging into the Gulf of Mexico with drier air are a couple of the reasons why the season quiets down.
(MORE: Mid-Season Hurricane Update)

Where Do We Look For Development of These Storms?

As the Cape Verde portion of the hurricane season begins to fade away, we start to look closer to the United States for development.
(MORE: Why Tropical Waves Are Important During Hurricane Season)
The most common formation areas for named storms in October are the Caribbean Sea, Gulf of Mexico and the western Atlantic Ocean. In November, we continue to keep our eyes on the Caribbean Sea and the western Atlantic for potential development.

As the jet stream dips farther south in the fall, it can help to pull northward any tropical systems that develop in the northwest Caribbean and the Gulf of Mexico toward the southern United States.

Late-Season U.S. Hurricane Strikes

A total of 53 hurricanes have struck the U.S. in October since 1851, according to NOAA. Of these, 16 have been major Category 3 or higher hurricanes. Only five hurricanes have struck the U.S. in November since 1851.
Kate in 1985 was the latest hurricane, in any season, to make landfall in the U.S. on record, coming onshore only a week before Thanksgiving. The latest major Category 3 or higher hurricane to make a U.S. landfall was the Tampa Bay Hurricane in 1921, which hit the west-central coast of Florida on Oct. 25. Wilma in 2005 was the second-latest major hurricane landfall on Oct. 24.
For South Florida, October is actually the month with the most hurricane direct hits. According to NOAA, a total of 27 hurricanes have passed within 100 nautical miles of Miami since 1851.