Notorious October hurricanes

 

Hurricane Michael at landfall, October 2018 (Source: WUSA9/NOAA)

October is the third most active month of the six-month Atlantic hurricane season, behind only August and September. The frequency and intensity of tropical storms and hurricanes often decreases as we get deeper into October. That’s not to say there haven’t been intense and high impact October hurricanes in the Atlantic, with Milton being the most recent.

Zeta (2020):  Zeta reached peak intensity on October 28 as a major Category 3 hurricane when it made landfall in Louisiana. Its highest sustained winds were 115 mph with a minimum central air pressure of 970 millibars (mb). Although Zeta quickly weakened after its landfall, it remains noteworthy for being the latest in the season a major hurricane made landfall in the contiguous United States. Zeta caused $5.1 billion in U.S. damages (2023 dollars), according to NOAA, along with five fatalities.

Michael (2018):  Hurricane Michael became only the fourth Category 5 hurricane to make landfall in the United States and first since Hurricane Andrew in 1992. Michael reached peak intensity when it made landfall along the Florida panhandle with sustained winds of 160 mph and a minimum central air pressure of 919 millibars (mb). That part of Florida had seen several Category 3 hurricanes, but never a Category 4 or 5 storm. Michael caused $30.2 billion in U.S. damages (2023 dollars) and claimed 16 lives during the storm, according to NOAA.

Wilma (2005) – Fortunately, Wilma weakened significantly from its peak intensity as a Category 5 hurricane before it reached southwest Florida as a Category 3 storm on October 24. Wilma was noteworthy for being the last hurricane to make landfall anywhere in Florida until Hermine in 2016. It produced $29.3 billion in damages (2023), placing it among the Top 15 costliest U.S. hurricanes. 

Opal (1995):  Opal was one of five major hurricanes to form during the very active 1995 season. It was the strongest hurricane of the season with peak winds of 150 mph and a minimum central air pressure of 916 millibars. Fortunately, it weakened to Category 3 intensity before making landfall near Pensacola, Florida on October 4. Opal brought a significant storm surge to the U.S. Gulf Coast, with additional impacts far inland. The D.C. Metro Area saw severe weather from the remnants of Opal on October 5.

Milton keeps rare company

 

Category 5 Hurricane Milton (Source: NOAA)

Hurricane Milton’s intensity over the Gulf of Mexico ranks high among past storms in the Atlantic Ocean Basin. A Category 5 hurricane with sustained winds of 175 mph, it’s minimum central air pressure is a very low 911 millibars (mb). By comparison, standard sea level air pressure is approximately 1013 millibars.

Although Milton is expected to weaken to a Category 3 storm prior to landfall on Florida’s Gulf Coast, the surge will be comparable to a more intense storm. That’s similar to Hurricane Katrina (2005) that was a Category 5 storm over the open Gulf of Mexico but weakened to a still major Category 3 storm. However, since Katrina was such an intense storm with a large diameter, its surge was more typical of landfalling Category 4 or 5 hurricane.

Milton’s lowest observed air pressure, so far, of 911 millibars ranks it as the 11^th lowest on record in an Atlantic hurricane behind such dangerous storms as Wilma, Gilbert and Katrina. Fortunately, the National Hurricane Center expects Milton to weaken before landfall. However, it will remain an intense and large diameter storm making evacuations and preparations essential for communities in harm’s way, as instructed by local officials.

Milton’s peak sustained winds of 175 mph have tied it with several other Atlantic hurricanes (e.g., Camille, Andrew and Katrina) for fourth highest sustained wind speed on record. It’s rapid intensification from minimal hurricane to Category 5 monster in one day was due to ideal conditions, including very warm ocean water and favorable winds aloft that allowed for outflow to occur.

This is the second Category 5 hurricane of the 2024 Atlantic season, along with Beryl earlier in the year. That makes 2024 one of only a small number of seasons to see multiple Category 5 hurricanes, such as 2019, 2017, 2005, and 1932.