Hurricane Katrina

When we think about tropical cyclones in the Atlantic basin, perhaps a few stand out in our minds, like Hurricane Katrina. Hurricane Katrina was one of the strongest storms to ever make landfall in the United States. From the extensive flooding, and the mass movement of people out of the affected areas, to the large economic impact and high death toll, let's take a look at what made Hurricane Katrina the costliest hurricane in the United States' history. 

Hurricane Katrina Hurricane Katrina

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Table of contents

    Hurricane Katrina facts

    Let's take a look at some of the hard hitting facts about Hurricane Katrina. Hurricane Katrina was one of the biggest natural disasters to impact the United States. It affected an area of about 90,000 sq. miles/ 233,000 sq km and permanently displaced 400,000 persons. Hurricane Katrina caused an estimated US $81 billion in property damages and an estimated US $170 billion in overall damages.

    Hurricane Katrina date

    Hurricane Katrina was the twelfth tropical cyclone and fifth hurricane of the 2005 Atlantic hurricane season. It was also the third storm to turn into a major hurricane in 2005. Hurricane Katrina formed near the Bahamas as a tropical depression on 23 August 2005 and dissipated near the Great Lakes in the northern United States on 31 August 2005.

    Hurricane Katrina Hurricane Katrina track on a map StudySmarterFig. 1 - Hurricane Katrina's track- 23 Aug. 2005 - 31 Aug. 2005

    Hurricane Katrina category

    Hurricane Katrina intensified quickly, becoming a Category 1 hurricane within two days of its formation. It then went on to become a Category 3 hurricane soon after that. At its strongest, before making landfall in the gulf coast states, Hurricane Katrina was a Category 5 hurricane, according to the Saffir-Simpson Hurricane Wind Scale, with maximum sustained winds exceeding 160 mph or 257 km/h.

    The Saffir-Simpson Hurricane Wind Scale ranks hurricanes from category 1-5 based on their maximum sustained wind speed only. The categories are as follows:

    CategoryWind Speed
    174-95 mph119-153 km/h
    296-110 mph154-177 km/h
    3 (major hurricane)111-129 mph178-208 km/h
    4 (major hurricane)130-156 mph209-251 km/h
    5 (major hurricane)> 157 mph> 252 km/h

    Did you know: The centre of a tropical cyclone is called the eye?!

    Hurricane Katrina affected areas

    The areas (states) directly affected by Hurricane Katrina were Florida, Georgia, Alabama, Louisiana and Mississippi. Of these, Louisiana and Mississippi experienced the most significant impacts.

    Florida, Georgia and Alabama

    Two days after its formation, Hurricane Katrina made its first landfall between Miami and Ft. Lauderdale in Florida as a Category 1 storm. Here, Katrina's heavy rains and winds caused flooding and damaged crops and downed trees and electricity lines. The latter left over 1 million people without electricity. The storm bands also produced a tornado which caused damage in the Florida Keys.

    Western Georgia experienced heavy rains and damaging winds from Hurricane Katrina. The state was also hit by 20 tornadoes due to the hurricane, which caused two deaths and destroyed several homes and businesses.

    In Alabama, there was flooding from the storm surge. Katrina also downed trees and electricity lines, resulting in power outages for up to over a week in some places. On Dauphin Island, the hurricane destroyed or damaged many beachfront homes. The bands of Katrina also produced 11 tornadoes in the state.

    Hurricane Katrina cars underwater in storm surge floodwaters in Mobile Alabama StudySmarterFig. 2 - storm surge floodwaters in Mobile, Alabama.

    Mississippi and Louisiana

    As stated above, Mississippi and Louisiana experienced the largest impacts from Hurricane Katrina. It made landfall in these states as a Category 3 storm.


    Mississippi's gulf coast region experienced the strongest part of Katrina. While all the state's counties were affected, the three most heavily impacted were Hancock, Harrison and Jackson Counties- all located along the coast. This is because perhaps the most devastating impact of Katrina in Mississippi was the 24-28 ft/7.3- 8.5 m storm surge.

    A storm surge is a temporary rise in seawater above normal sea level (often by several metres) due to a storm.

    Approximately 90% of the buildings on the Biloxi-Gulfport coastline were destroyed, and there was flooding up to 6-12 miles/ 9.5-19 km inland. Although there was widespread evacuation before Katrina, some residents remained and had to resort to climbing into their attics, on top of their roofs or onto nearby trees to escape the surge waters.

    Additionally, numerous floating casino barges were washed inland as a result. In other parts of Mississippi, streets and bridges were washed away. The hurricane downed trees and electricity lines and caused power outages which took up to 3 weeks to be fully restored.

    Hurricane Katrina destruction of the Ocean Springs Bridge in Mississippi StudySmarter

    Fig. 3 - the destruction of the Ocean Springs bridge, Mississippi


    In Louisiana, Hurricane Katrina caused catastrophic flooding, destroyed numerous buildings and downed trees and electricity lines. People were without power for many weeks. In addition, there was an extensive loss of coastal wetland due to the storm. Hurricane Katrina also affected oil production, damaging about 20 oil rigs throughout the Gulf Coast. Operations at the Louisiana Offshore Oil Platform also halted. This caused the average national gas price to exceed US $3.00 for the first time in the country's history. Louisiana also accounted for over 85% of the deaths caused by Hurricane Katrina. The south-eastern parishes of St. Tammany, Jefferson, Terrebonne, Plaquemines, Lafourche and St. Bernard, along with the city of New Orleans, experienced the most damage.

    Hurricane Katrina New Orleans

    When you think about Hurricane Katrina, the first thing that probably comes to mind is its impact on the city of New Orleans, Louisiana, which experienced the worst impacts of the hurricane.

    New Orleans is located about 105mi/169 km north of the Gulf of Mexico and is surrounded by the Mississippi River, Lake Borgne and Lake Pontchartrain. A large part of the city of New Orleans is between 10-16 ft/3-5 metres below sea level, making it almost like a bowl. To protect the city from flooding, levees and sea walls were built along the Mississippi River and the two lakes to ensure that these water bodies don't overflow their banks in times of flood.

    A levee is a ridge of sediments along the banks of a river or other water body to prevent it from flooding. Levees accumulate naturally but can also be man-made.

    On 28 August 2005, approximately 1.2 million people left New Orleans as part of the Mayor's mandatory evacuation order. However, many residents either chose to remain or were unable to leave the city because they were elderly or didn't have access to transportation. Of the remaining ones, a few thousand sought shelter at either the Louisiana Superdome or the New Orleans Convention Centre. The others remained in their homes.

    While New Orleans was spared a direct hit from Hurricane Katrina, the storm surge and 8-10 in/20-25 cm of rain caused 50 levees to fail because of the excess pressure. This, in turn, caused large amounts of flood water to run into the city. By the afternoon of 29 August 2005, about 20% of New Orleans was underwater, and by the next day, 80% of the city was under up to 20 ft/6 m of water. The Ninth Ward, Lakeview and St. Bernard Parish experienced the worst flooding. Many residents who remained in their homes had to be rescued by boat and some by helicopter from the roofs of their houses. However, many people died, particularly the elderly, as they could not escape the floodwaters.

    The rescued were taken to the Superdome. However, they had to be relocated after the roof started leaking. There were reports of food and medical supply shortages for the displaced individuals. Hospitals had no electricity and had to find alternative locations for their patients. Looting also took place. The pump stations used to pump the water out of the city were damaged during the flooding, and therefore the water remained stagnant in New Orleans for several weeks after the passing of the storm. This in itself caused other types of health problems.

    Hurricane Katrina New Orleans under flood water StudySmarterFig. 4 - New Orleans under floodwaters

    Hurricane Katrina deaths

    To date, the total number of deaths, directly and indirectly, caused by Hurricane Katrina is 1833, broken down by state in the following table.

    StateNumber of Deaths

    Table 2

    It is estimated that more than half of the deaths related to Hurricane Katrina were people over 60 years of age.

    Response to Hurricane Katrina

    The response to Hurricane Katrina involved coordination between government entities at all levels, non-governmental organisations (NGOs) and private volunteers. International countries also offered aid. Some, not all, responses to Hurricane Katrina were as follows:

    • Federal Emergency Management Agency (FEMA) provided logistical supplies and mortuary trucks.
    • National Guard was mobilised to restore law and order in New Orleans.
    • National Disaster Medical System was activated, and medical teams were deployed to provide immediate medical care.
    • The federal government approved and deployed US $62.3 billion in aid.
    • Coast Guard sent helicopters and boats and organised search and rescue teams to rescue people stranded by the floodwaters.
    • Local governments from surrounding states deployed ambulances, disaster supplies and search teams.
    • NGOs such as the American Red Cross and the Salvation Army provided food and shelter for displaced individuals.
    • International aid and support were also sent from places such as Kuwait, Canada, the United Kingdom and Mexico, to name a few.

    Hurricane Katrina Members of US Marine Corps looking in the water for survivors in New Orleans StudySmarterFig. 5 - members of the US Marine Corps search for survivors in New Orleans

    Authorities in the United States were criticised for responding slowly with post-disaster relief, particularly related to New Orleans.

    Hurricane Katrina - Key takeaways

    • Hurricane Katrina was one of the costliest and deadliest natural disasters in the United States' history.
    • At its strongest, Hurricane Katrina was a category 5 storm with maximum sustained winds of over 160 mph/257km/h
    • Hurricane Katrina impacted the states of Alabama, Florida, Georgia, Louisiana and Mississippi. Louisiana and Mississippi suffered the most damage from the hurricane.
    • 80% of the city of New Orleans was flooded when the levees failed during Hurricane Katrina.
    • Hurricane Katrina caused over US $170 billion in overall damages and claimed 1833 lives - over 85% of whom were from Louisiana.
    • Relief efforts were mobilised between the government, NGOs, private volunteers and international countries.


    1. Fig. 2 - storm surged flood waters in Mobile, Alabama ( by au_tiger01 ( Licensed by CC BY 2.0 (
    2. Fig. 3 - destruction of the Ocean Springs bridge, Mississippi ( by Klobetime ( Licensed by CC BY-SA 2.0 (
    3. Fig. 5 - members of the US Marine Corps search for survivors in New Orleans ( by expertinfantry ( Licensed by CC BY 2.0 (
    Frequently Asked Questions about Hurricane Katrina

    When was Hurricane Katrina? 

    Hurricane Katrina formed on 23 August 2005 and dissipated on 31 August 2005. 

    What areas were most affected by Hurricane Katrina? 

    Louisiana and Mississippi were the most affected states. New Orleans experienced the greatest impact from the hurricane. 

    How destructive was Hurricane Katrina? 

    Hurricane Katrina causes about USD $170 billion in damages, making it the costliest disaster in the history of the United States. It also killed 1833 people. 

    What made Hurricane Katrina deadly? 

    Hurricane Katrina was deadly because it caused storm surges that caused extensive flooding far inland and in areas where many people refused to evacuate. 

    What was done after Hurricane Katrina? 

    After Hurricane Katrina relief efforts were coordinated among the US government, NGOs, private volunteers and international countries. However, the US government was criticised for its slow disaster-relief response. 

    Test your knowledge with multiple choice flashcards

    Where did Hurricane Katrina develop?

    What category storm was Hurricane Katrina when it hit Florida?

    TRUE or FALSE: Hurricane Katrina caused tornadoes in Alabama, Georgia and Florida.


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