Key Dates and Landfalls of Hurricane Isaac
Hurricane Isaac made landfall twice in the United States in late August 2012. The first landfall occurred on August 28 near the mouth of the Mississippi River in Louisiana as a Category 1 hurricane. A second landfall followed on August 29 in Louisiana southeast of New Orleans, with parts of Louisiana, Mississippi, Alabama, and Florida experiencing significant impacts. Below is a concise factual timeline of the storm's development, track, and landfalls.
| Attribute | Verified Detail | Source Type |
|---|---|---|
| Name | Hurricane Isaac | Official Atlantic Basin Best Track (HURDAT2) |
| Formation | August 21, 2012 (tropical depression) | National Hurricane Center (NHC) |
| First U.S. landfall | August 28, 2012, near the mouth of the Mississippi River, Louisiana (85 kt, 965 mb) | NHC Postseason Report |
| Second U.S. landfall | August 29, 2012, southeast of New Orleans, Louisiana (80 kt, 967 mb) | NHC Postseason Report |
| Peak intensity | Category 1, 85 kt, 965 mb | NHC Best Track |
| Total fatalities (U.S.) | Approximately 41 | NHC Summary/Storm Data |
| Major impacts | Storm surge, river flooding, widespread power outages, especially in Louisiana and Mississippi | Federal Emergency Management Agency (FEMA), NOAA reports |
Formation and Early Track
Tropical Development
Isaac originated from a tropical wave that moved off the west coast of Africa in mid-August 2012. Slow organization occurred as the wave moved across the eastern Atlantic and into the Caribbean. Convection increased near the Lesser Antilles, and the system became a tropical depression on August 21. By August 25, it had strengthened into a tropical storm and was named Isaac.
Caribbean Passage
Isaac tracked west-northwestward through the eastern Caribbean in late August, bringing locally heavy rainfall and gusty winds to the Lesser Antilles. It passed south of Hispaniola and eastern Cuba, where rainfall totals reached 4 to 8 inches in many areas, with higher isolated amounts. These conditions elevated flood risks well before U.S. landfalls.
First U.S. Landfall: Louisiana Coast
Approach and Slow Motion
Isaac remained a large tropical cyclone as it approached the northern Gulf Coast. Steering currents weakened, causing the storm to drift slowly toward the Louisiana coast. This slow motion increased the duration of onshore flow and storm surge, elevating flood risks days before landfall. Ahead of the storm, mandatory evacuations were issued for coastal parishes, and ports suspended operations.
Landfall Details
At approximately 7:15 p.m. CDT on August 28, Isaac made landfall near the mouth of the Mississippi River in Plaquemines Parish, Louisiana, with maximum sustained winds near 85 kt (98 mph) and a minimum central pressure of 965 mb. The hurricane produced a life-threatening storm surge, with a maximum recorded surge of approximately 11.5 feet at Shell Beach, Louisiana. Gusts near hurricane force damaged structures, downed trees, and caused widespread power outages.
Second U.S. Landfall and Inland Movement
Continued Impacts in Louisiana
After the first landfall, Isaac’s circulation remained broad and its forward motion inconsistent, leading to additional periods of heavy rainfall and storm surge along the Louisiana coast. On August 29, the system made a second landfall near the southeastern Louisiana coast, bringing continued coastal flooding and strong winds.
Track Across the Southeastern U.S.
Isaac slowly moved northwestward across Louisiana and into Mississippi, dropping 10 to 20 inches of rain in many locations. Major river flooding occurred along the Mississippi River and its tributaries, particularly in the Lower Mississippi Valley. The storm then accelerated northward, bringing heavy rain and gusty winds into Tennessee, Kentucky, and the Ohio Valley before transitioning into a post-tropical cyclone on September 1.