1. The 18th tropical storm of the season, Tropical Storm Gordon, formed just east of the Louisiana coast on Aug. 28, becoming the 13th named storm of the season. Gordon strengthened to a hurricane the same day and then made landfall on the Louisiana coast as a Category 1 hurricane. Nine days later, four more storms formed — “the most of any single season since 1971,” says Alan Kort, a meteorologist with the National Hurricane Center. In comparison, the U.S. experienced nine named storms during all of 2017.
2. On Sept. 1, Hurricane Florence struck the Carolinas as a Category 4 storm. It was the second-most powerful Atlantic hurricane on record, surpassing Hurricane Camille’s force in 1969. Hurricane Florence’s eventual death toll reached at least 39.
3. “As long as we continue to encounter an Atlantic basin with mature Atlantic hurricanes, as well as strong extratropical cyclones such as Depression Gordon that develop in the eastern Atlantic, it’s not surprising that we have 20 tropical storms on the books,” says Phil Klotzbach, a hurricane research scientist with Colorado State University. He adds that the U.S. has more tropical storms per year than it did in the 1800s, but that number has fallen in recent decades because of development of barriers such as the International Date Line.
4. Tropical Storm Isaac made landfall on the northwestern Caribbean Sea on Sept. 4 as a Category 1 hurricane.
5. Tropical Storm Gordon formed in the Atlantic, but was retired by a potent cold front moving in from the Midwest. Gordon formed at the same time that Hurricane Florence made landfall, but didn’t make it into the Gulf of Mexico and then enter the typical eastern U.S. cycle of a developing storm.
6. From Sept. 7-11, Tropical Storm Leslie developed in the Atlantic as a depression near the Azores. It was later downgraded to a tropical storm and on Sept. 11 lost its tropical strength.
7. By Sept. 12, Tropical Storm Nadine formed in the open Atlantic off the coast of the coast of South Africa. It was active for much of the day, but dissipated by 4 p.m. that day.
8. On Sept. 12, Tropical Storm Gordon dissipated.
9. Nine days later, Hurricane Florence made landfall on the South Carolina coast as a Category 4 storm. During the weekend, Tropical Storm Gordon reformed as Tropical Storm Helene moved into the Atlantic.
10. Hurricane Helene became the 15th named storm of the season on Sept. 14, as it swung south from Georgia into the open Atlantic. It was later downgraded to a tropical depression.
11. Just seven days later, Tropical Storm Isaac made landfall on the northwest Caribbean Sea as a Category 1 hurricane. Isaac reached Category 2 in the Caribbean, but later lost its strength and dissipated.
12. On Sept. 22, Tropical Storm Ida formed in the open Atlantic. It remained east of the U.S. and died within two days.
13. On Sept. 24, Hurricane Maria brought devastating damage to Puerto Rico. At least 2,975 people perished, the greatest number of fatalities of any disaster in U.S. history. Hurricane Maria was officially a Category 4 storm at landfall.
14. Hurricane Helene moved into the Atlantic and died two days later.
15. Hurricane Florence made landfall in the Carolinas as a Category 4 storm. In total, the storm caused 42 deaths.
16. Hurricane Leslie made landfall on the northwest Caribbean Sea on Sept. 28 as a tropical storm.
17. Hurricane Jimena weakened to a tropical depression by Oct. 3.
18. Tropical Storm Gordon formed in the Atlantic, but made landfall in the Gulf of Mexico and was then downgraded to a tropical depression.
19. Hurricane Leslie was downgraded to a tropical storm on Oct. 3, but remained in the Gulf of Mexico.
20. Hurricane Isaac slammed into the Canary Islands off the western Caribbean Coast as a Category 2 hurricane on Oct. 7.