September’s significant hurricanes

 

Hurricane Helene, September 2024 (Source: NOAA)

Although it may not seem like it this season, September is statistically the busiest month of the Atlantic hurricane season. Whenever a tropical storm or hurricane is particularly destructive or deadly, the World Meteorological Organization retires its name. There are four September hurricanes that have impacted the United States in the last decade that have had their names retired.

Hurricane Helene (2024): Helene developed in the western Caribbean Sea and intensified into a major hurricane as it tracked northward into the Gulf. It reached its peak intensity as a Category 4 hurricane with sustained winds of 140 mph and a minimum central air pressure of 939 millibars (mb). By comparison, standard sea level air pressure is approximately 1013 mb. Helene made landfall in northwestern Florida near the town of Perry and was a prolific rainmaker in areas well inland. Widespread flooding occurred from the remnants of Helene as far north as the Carolina’s and Tennessee Valley. According to NOAA, the storm is responsible for approximately 250 deaths in the United States along with $78.7 billion in damages (2024 dollars).

Hurricane Ian (2022): Ian developed in the Caribbean Sea and was upgraded to hurricane status south of Cuba. It intensified rapidly after crossed Cuba as it headed toward southwestern Florida. Ian briefly reached Category 5 intensity (160 mph / 937 mb), but made landfall as a Category 4 hurricane on Cayo Costa Island in southwestern Florida. Ian was an exceptionally destructive storm and did an estimated $119.6 billion in damages (2024 dollars). That not only made it the most destructive hurricane in Florida state history (ahead of other catastrophic storms like Irma, Charley and Andrew), but Ian remains the third costliest hurricane overall in the United States.

Hurricane Florence (2018): A long lasting Cape Verde hurricane that lasted more than two weeks, Florence was a Category 4 at peak intensity over the open Atlantic. It had sustained winds of 150 mph and a minimum central air pressure of 937 mb. Fortunately, it weakened to Category 1 intensity before its landfall in North Carolina on September 14. However, because the atmospheric steering currents were very weak, it meandered across the Carolinas and Mid-Atlantic Region for several days where devastating flooding resulted. According to NOAA, Florence did an estimated $30.0 billion in damages in the United States (2024 dollars).

Hurricane Irma (2017): Irma was another long-lasting Cape Verde hurricane that reached Category 5 intensity on two separate occasions. At peak intensity, Irma had sustained winds of 180 mph and a minimum central air pressure of 914 millibars (mb). Irma left a deadly trail of destruction across much of the Caribbean and ultimately made landfall in Florida as a Category 4 hurricane. It was the first Category 4 hurricane to make landfall in Florida since Charley in 2004. Ultimately, Irma killed dozens in the United States and did $64.0 billion in damages (2024 dollars).

Weather Quiz

Hurricane Isabel, September 2003 (Source: NOAA)

Which was the last “major” hurricane to make landfall in North Carolina?

A.  Fran

B.  Floyd

C.  Irene

D.  Florence

A record-setting hurricane season?

A summer evening along Dewey Beach, Delaware (2025)

The Atlantic Ocean is fast-approaching setting a new record for the latest a hurricane season has gone without a hurricane. The existing record for latest the first hurricane has developed is September 11. Since NOAA’s National Hurricane Center doesn’t expect any named storms to develop this week, this season will eclipse the long-standing record.

The three previous times the Atlantic’s first hurricane developed on September 11 was in 2013 (Humberto), 2002 (Gustav) and 1984 (Diana). Each season featured a near to below average amount of tropical activity. Only 2002 had a moderate episode of El Nino. That’s unlike the current El Nino that’s already strong and is expected to strengthen further by the end of the year. That means conditions will remain largely unfavorable for tropical storm and hurricane development.

This season has already had four short-lived tropical storms, and such below average tropical activity in the Atlantic is commensurate with a moderate to strong El Nino. However, this hurricane season has approached uncharted territory without a hurricane since last October. NOAA expected this hurricane season to be a quiet one given the intensifying El Nino, but it wasn’t expected to be this calm.

Although there have been quiet seasons before, there hasn’t been a season in the satellite era, dating back to the 1960s, without a single Atlantic hurricane by September 11. That’s an important distinction since there were almost certainly storms that remained undetected over the open ocean before there were weather satellites that could identify them.

It’s also worth noting that some past quiet seasons, still produced storms that were damaging and deadly. Such was the case when Hurricanes Andrew (1992) and Alicia (1983) each made devastating landfalls in the United States.

This week is also significant for being the climatological peak of the hurricane season when atmospheric and environmental conditions are traditionally the most favorable for development. However, the tropical Atlantic remains unusually quiet. The Atlantic hurricane season runs through November 30.