Hurricane Katrina 20 years later

Written by Megan K. Ironside

Last updated 8/28/2025, 4:04:27 PM

After its first landfall on the Southeastern coast of Florida, Hurricane Katrina entered the Gulf and a combination of atmospheric and oceanic conditions allowed it to intensify into one of the deadliest and costliest hurricanes in U.S. history. While making its second and third landfall with Category 3 winds, an historic storm surge and breached levees wreaked havoc on the Gulf Coast of Louisiana and Mississippi, decimating entire towns and causing 1,392 deaths and over $125 billion dollars in damages. Let’s look back on the meteorological history of this landmark hurricane, its path, and the aftermath.

Photo courtesy of NOAA, Office for Coastal Management, DigitalCoast

THE BEGINNINGS

Katrina began on August 19, 2005, when a tropical wave coming from West Africa; the mid-tropospheric remnant of a separate, failed system, Tropical Depression Ten; and an upper-level trough that had initially destroyed Tropical Depression Ten came together. On August 23, the National Hurricane Center (NHC) officially designated it as Tropical Depression Twelve. By the next day, August 24, the storm was 65 nautical miles east-southeast of Nassau and had strengthened to become Tropical Storm Katrina. Once it reached the warm coastal waters of southeastern Florida the storm became more organized and a well-defined eye was visible on radar imagery. On August 25 around 4:30 PM EDT the storm reached hurricane status. Katrina made landfall two hours later.

Radar and satellite imagery of Katrina at first landfall in Florida as a Category 1.

FIRST LANDFALL

On August 25 at 6:30 PM EDT, Katrina hit the Eastern Florida coast between Hallandale Beach and Aventura as a Category 1 hurricane. At landfall, it had maximum sustained winds of 80 mph and a central pressure of 984 mb. Significant precipitation, with widespread totals of 5 to 10 inches and isolated amounts exceeding 15 inches, caused localized flooding. After the six hours Katrina was on land in Florida, it weakened to a tropical storm. Fourteen fatalities were recorded.

FROM TROPICAL STORM TO CATEGORY 5

On the morning of August 26, the center emerged into the southeast Gulf of Mexico north of Cape Sable, FL. Just 48 hours later, Katrina would transform from a minimal tropical storm into the fourth most powerful tropical cyclone ever observed in the Atlantic Basin. The rapid development was made possible by the Gulf of Mexico containing some of the most favorable oceanic and atmospheric conditions possible for hurricane development.

Sea surface temperatures in the Gulf were well above the 26.5 C threshold needed for tropical cyclone development. Then Katrina’s path took it directly over a feature known as the Great Loop Current which is a deep current of very warm water that extends northward from the Caribbean Sea into the Gulf of Mexico. 

A hurricane's powerful winds typically cause significant upwelling, churning the ocean and bringing cooler water from below to the surface. This process limits a storm's potential intensity. In Katrina's case, its path over the high-OHC waters of the Loop Current effectively negated this natural braking mechanism. The water was so warm to such a great depth that it provided a continuous supply of energy, allowing the storm to grow.

A large upper-level anticyclone was situated over the entire Gulf creating an area of very weak vertical wind shear. This lack of disruptive winds at high altitudes allowed the storm’s vertical structure to remain intact and so Katrina intensified even more.

Hurricane Katrina imaged by NOAA-16 AVHRR instrument. (Image credit: NOAA/NESDIS Environmental Visualization Laboratory)

Now a Category 1 hurricane again, Katrina went through two rapid intensification cycles: one on August 27 where it strengthened into a Category 3 and the second on August 28, following an internal structural change known as an eyewall replacement cycle where it intensified into a Category 5.

By 1:00 PM CDT Sunday, August 28, Hurricane Katrina reached its peak intensity about 170 nautical miles southeast of the mouth of the Mississippi River with maximum sustained winds of 175 mph and a minimum central pressure of 902 mbar, which is the fourth lowest pressure ever recorded in the Atlantic Basin.

As Katrina intensified, it also grew in size. The storm's wind field expanded, stretching some 400 miles across at its peak with tropical storm-force winds extending outward up to 230 miles from the center, and hurricane-force winds extending up to 105 miles. This immense size meant that the storm was imparting a tremendous amount of kinetic energy into the northern Gulf, piling up a vast dome of water that would later be unleashed as a catastrophic storm surge.

Hurricane Warning issued by the NWS in Slidell, LA, 24 hours before Katrina's second landfall in Louisiana. Photo courtesy of NWS.

LANDFALL 2 & 3: THE GULF COAST

On Monday, August 29, at 6:10 AM CDT, Katrina made landfall in Plaquemines Parish, part of the Mississippi River Delta, near the town of Buras, Louisiana, as a Category 3 hurricane with 127 mph winds and 920 mbar pressure–the third lowest pressure ever recorded for a U.S. landfalling hurricane. 

Weakening only slightly and after crossing Breton Sound, at 9:45 AM CDT, Hurricane Katrina made its third and final landfall near the mouth of the Pearl River on the borders of Louisiana and Mississippi as a Category 3 with sustained winds of 121 mph and pressure of 928 mbar. The storm remained hurricane strength for over 150 miles inland, finally weakening to a tropical storm near Meridian, Mississippi, and later becoming a tropical depression near Clarksville, Tennessee.

New Orleans, LA-September 8, 2005- Neighborhoods and roadways throughout the area remain flooded as a result of Hurricane Katrina. Local ID: 311-MAD-192002. Jocelyn Augustino/FEMA

Katrina's catastrophic devastation stemmed primarily from its unprecedented storm surge. This massive wall of water was characteristic of a much stronger Category 5 storm, obliterating everything in its path. Four key factors contributed to this historic surge: the immense size of Katrina, its intensity, the significant wave action, and the shallow depths of the northern Gulf.

This storm surge penetrated miles inland, reaching at least six miles in many parts of coastal Mississippi and up to 12 miles along bays and rivers. Over 200 miles of the Gulf coastline, stretching from southeastern Louisiana to the Florida panhandle, experienced a storm surge exceeding ten feet. Along a 20-mile stretch of the Mississippi coast, the surge reached an astonishing 24 to 28 feet above normal tide levels, completely destroying communities in Hancock and Harrison Counties, Mississippi.

Some of the most catastrophic damage occurred in New Orleans where levees and floodwalls failed, resulting in 80 percent of the city being underwater. Over 200,000 homes in New Orleans and other Gulf Coast cities were damaged or destroyed. This extensive flooding also caused widespread power outages for three million people, making it extremely difficult, if not impossible, for emergency resources to reach stranded citizens. Forty percent of the deaths in Louisiana were drowning deaths. 

Katrina’s destruction extended to oil rig platforms, refineries, gambling barges, and vast areas of forest, impacting these industries for years. 

New Orleans, LA, August 30, 2005–Rescue operations continue at a staging area set up for local, state and federal operations. Jocelyn Augustino/FEMA

In addition to wind and surge, Katrina produced widespread heavy rainfall and a significant tornado outbreak. Rainfall totals of eight to 12 inches were common along and to the east of the storm's track as it moved inland from the Gulf Coast. Coastal areas of Mississippi saw six to nine inches. 

From August 26 to August 31, Katrina's outer rainbands spawned a moderate tornado outbreak, producing 57 confirmed tornadoes across eight states: Florida, Alabama, Mississippi, Georgia, North Carolina, Virginia, Maryland, and Pennsylvania. The majority of these tornadoes were weak (rated F0 or F1). Georgia recorded 18 tornadoes touching down on August 29. This included a deadly F2 tornado near Roopville in Carroll County, which caused one fatality and significant damage. 

THE AFTERMATH

Katrina not only affected homes and businesses, it altered the population of the Gulf Coast. Approximately 1.5 million people from Alabama, Mississippi, and Louisiana evacuated in advance of Katrina. Of these evacuees, roughly 40 percent (primarily from Louisiana) were unable to return to their homes. While 25 percent of those displaced relocated within 10 miles of their original county, another 25 percent moved at least 450 miles away. A significant portion, ten percent, relocated even further, traveling 830 miles or more.

Katrina along with other storms of the devastating 2004 and 2005 seasons (which also includes Charley, Rita and Wilma) highlighted the urgent need for more advanced storm prediction. In response, the Hurricane Forecast Improvement Project (HFIP) was launched in 2007. This NOAA-led initiative aimed to foster collaboration among different weather agencies to enhance hurricane forecasting and research.

The HFIP's mission was to provide the public with more lead time and better information in the face of a storm threat. They achieved this by rapidly transitioning cutting-edge computer models and new forecasting techniques from theoretical development into practical application. The dramatic improvements in the accuracy and reliability of hurricane forecasts we see today are a direct result of this project, a powerful and lasting legacy born from one of America's worst natural disasters.

Hurricane Katrina was more than a historic storm; it was a force of nature that permanently altered how Americans perceive hurricanes. Its sheer power and immense scale, demonstrated over three separate landfalls, revealed the catastrophic potential of an Atlantic hurricane in a way no storm had before. Katrina left behind not just physical wreckage, but an indelible mark on our collective memory, forever changing our understanding of and respect for the awesome power of weather.