Hurricane Katrina formed over the Bahamas on August 23, 2005, and rapidly intensified as it moved northwest toward Louisiana. On August 29, the storm made landfall near Buras, Louisiana, as a Category 3 hurricane, with sustained winds around 125 mph, then crossed into Mississippi as a powerful tropical cyclone. In New Orleans, the storm made its closest approach just east of the city, but the decisive catastrophe was widespread levee failure, not the eyewall. The strongest, most damaging impacts occurred in southeastern Louisiana and coastal Mississippi on August 29, with flooding and destruction continuing for days as the storm weakened slowly inland. This verified timeline explains when Hurricane Katrina happened, how long it lasted, and how its impacts unfolded across the region.
Key dates and timeline of Hurricane Katrina
Below is a concise, verified sequence of the most important moments in the Katrina event, covering formation through the main impacts and early response.
| Date or period | Event | Why it matters |
|---|---|---|
| August 23, 2005 | Tropical depression forms near the Bahamas | Marked the start of the system that would become Katrina |
| August 25, 2005 | Made landfall near Miami, Florida, as a Category 1 hurricane | Caused damage in South Florida and entered the Gulf of Mexico |
| August 26–27, 2005 | Rapid intensification in the Gulf of Mexico | Katrina grew to a Category 5 hurricane |
| August 28, 2005 | Peak intensity with maximum sustained winds near 175 mph | Historic strength; large-scale evacuations ordered |
| August 29, 2005, mid-morning | First landfall near Buras, Louisiana, as a Category 3 hurricane | Brought the strongest winds and storm surge to southeastern Louisiana |
| August 29, 2005, late morning | Second landfall near the Louisiana–Mississippi border as a strong tropical cyclone | Delivered destructive winds and a massive storm surge into Mississippi |
| August 29–30, 2005 | Levee and floodwall failures in New Orleans | Catastrophic flooding of large parts of the city |
| August 30–31, 2005 | Continued flooding, widespread rescue operations, and initial federal response | Highlighted major challenges in logistics, shelter, and coordination |
| September 1–2, 2005 | Large-scale evacuations and shelter openings nationally | Reflected the scale of the disaster and displacement |
How long did the hurricane last and where did it go?
Katrina’s duration is best described from tropical depression formation on August 23 to dissipation on August 31, 2005. It crossed southern Florida on August 25, re-intensified dramatically in the warm waters of the Gulf of Mexico, and struck Louisiana and Mississippi on August 29. The most intense portion of the storm’s life cycle spanned about one week from formation to final dissipation, with the most devastating impacts concentrated on August 29. Its path took it from the Bahamas into the Gulf of Mexico, then across southeastern Louisiana and Mississippi, with a lobe of storm surge and heavy rain affecting the Florida Panhandle and Alabama.
Measured impacts and documented facts
The following table summarizes core, widely reported attributes of Hurricane Katrina. Values are drawn from the National Hurricane Center and other authoritative post-event reviews.
| Attribute | Verified Detail | Source Type |
|---|---|---|
| Formation date | August 23, 2005 | National Hurricane Center best track |
| U.S. landfall 1 | August 25, 2005 (Florida), Category 1 | National Hurricane Center best track |
| U.S. landfall 2 | August 29, 2005 (LA/MS), near mid-morning | National Hurricane Center best track |
| Peak intensity | August 28, 2005, Category 5, 175 mph (280 km/h) | National Hurricane Center best track |
| Storm surge | 25–28 ft (7.6–8.5 m) in parts of Mississippi and Louisiana | Post-event analysis and NOAA reports |
| Fatalities (U.S.) | At least 1,392 confirmed direct and indirect deaths | Government and investigative reports |
| Cost (insured and uninsured damage) | Roughly $125 billion or more in 2005 USD | National Hurricane Center and insurance industry estimates |
| Displacement | Hundreds of thousands temporarily or long-term displaced | FEMA and Census data |
New Orleans and the levee failures
The most iconic and costly aspect of Katrina was the failure of the federally designed levee and floodwall system in New Orleans. On August 29 and into August 30, more than 50 breaches and overtoppings occurred, inundating approximately 80% of the city. The flooding was driven not by wind but by storm surge and rainfall combined with system design and maintenance shortcomings. This event reshaped conversations about infrastructure, equity, and disaster preparedness in the United States.
Federal, state, and local response in brief
In the immediate aftermath, challenges included delayed National Guard deployments, insufficient shelter and medical support, and chaotic evacuations. The scale of the disaster prompted the largest domestic response in U.S. history at the time, with tens of thousands of residents evacuated and billions in federal aid authorized. Long-term recovery efforts continue for years, including billions in rebuilding funds, revised building codes, and ongoing flood protection improvements.
Long-term lessons and changes
Katrina prompted comprehensive reviews and reforms. Key takeaways include the importance of clear evacuation plans, robust flood protection, improved communication among agencies, and attention to vulnerable populations. Many coastal communities updated building standards, and federal flood insurance and disaster policies were revised to address gaps exposed by the storm.
Understanding when Hurricane Katrina happened clarifies the sequence of decisions and natural forces that turned a major hurricane into one of the nation’s deadliest and costliest disasters. The storm’s timeline, measured in days and hours, produced impacts that continue to inform preparedness and policy long after the winds and waters subsided.