What begin as thunderstorms off the west coast of Africa can become hurricanes by the time they reach the Caribbean and the southeastern United States. Between 80 and 100 of these systems develop each year from June to November, but usually only a handful evolve into hurricanes that impact the United States. Check out some of nature's most catastrophic hurricanes.
Hurricane Katrina: August 2005
The year 2005 was another busy year for hurricanes, and Katrina, the fifth hurricane of the season, was one that will go down in history. Katrina made landfall near Buras-Triumph, Louisiana, with winds reaching 125 miles per hour before devastating the entire Gulf Coast of Mississippi. But all eyes were on New Orleans, situated below sea level and surrounded by rivers and lakes. So when Katrina made landfall slightly to the east, people in "The Big Easy" breathed a sigh of relief since it appeared that Mississippi had borne the major brunt of the storm.
But that changed a few hours later when the massive rainfall and storm surge caused Lake Ponchartrain to flood. When the city's levee system was breached in several places, 80 percent of New Orleans was left under water. The rest of the nation watched via television as residents stayed on rooftops in the scorching heat for days awaiting rescue. The U.S. government was severely criticized for its delayed reaction in sending aid. Katrina's wrath took more than 1,800 lives and hundreds are still missing. With more than $81 billion in damages, Katrina was the most expensive natural disaster in U.S. history.
Hurricane Ivan: September 2004
Ivan was the fourth major hurricane of the busy 2004 season. At one time a category 5 storm, by the time Ivan struck at Gulf Shores, Alabama, it had weakened to category 3 status with wind speeds reaching 130 miles per hour. But Ivan was the storm that wouldn't die!
After devastating much of the Florida panhandle, Ivan dumped water across the southeastern United States, then drifted over the Atlantic Ocean. Once back over the water, Ivan built enough energy to loop around to the south, move across the Florida peninsula, and pick up steam over the Gulf of Mexico -- again! Here, the remnants of the storm intensified and made landfall as a tropical storm along the coast of Louisiana. When Ivan finally dissipated over Texas, the storm had left 121 people dead and had caused more than $19 billion in damages.
Hurricane Andrew: August 1992
The third category 5 storm to hit U.S. shores and the first severe hurricane to hit southern Florida in 27 years, Hurricane Andrew brought along 145 mile per hour winds (with gusts up to 170 miles per hour) and a 17-foot storm surge. The day after Andrew ravaged southern Florida, it moved across to Louisiana, weakening to category 3 status but still packing 120 mile per hour winds. Andrew left 44 dead and caused $26.5 billion in damage, mostly in Florida. Around 250,000 people were left homeless, more than 700,000 insurance claims were filed, and even the coral reefs off the Florida coast sustained damage as far down as 75 feet.
Hurricane Hugo: September 1989
The strongest hurricane to hit the United States since Camille, Hugo struck near Charleston, South Carolina, as a category 4 storm with winds surpassing 135 miles per hour and a 20-foot storm surge. Hugo was also responsible for an estimated 85 deaths and $7 billion in damage, making it the costliest hurricane at the time.
Hurricane Camille: August 1969
With wind gusts exceeding 200 miles per hour and a 20-foot storm surge, Camille was the second category 5 hurricane to hit the United States. The massive storm struck along the mouth of the Mississippi River and flattened nearly everything along Mississippi's coastline. After pounding the Gulf Coast, Camille moved inland and caused heaving flooding and landslides in Virginia. In total, Camille caused more than $1.4 billion in damages and 259 deaths.
The New England Hurricane: September 1938
Normally, hurricanes thrive on the warm, tropical waters along the southeastern coast of the United States. But this storm had other plans, striking the northeastern United States instead. With winds gusting at more than 100 miles per hour, the eye of this hurricane struck Long Island, New York, but winds and massive rainfall wreaked havoc in Massachusetts, Connecticut, and Rhode Island, and caused damage in Montreal as well.
Dubbed the "Long Island Express," the storm killed 700 people, injured 700 more, and caused $306 million in damages. It also brought a 12- to 16-foot storm surge that destroyed more than 8,000 homes and 6,000 boats.
The Great Labor Day Storm: September 1935
In little more than 24 hours, this storm went from a category 1 to a category 5, where it remained when it struck the Florida Keys, making it the first hurricane of such intensity to strike the United States. With wind speeds reaching 200 miles per hour and a 15-foot storm surge, this cataclysmic hurricane caused $6 million in damages. Of the more than 420 people killed in the storm, about 260 of them were World War I veterans who were in the region building bridges as part of President Roosevelt's New Deal. The flimsy camps that housed the veterans were no match for this wicked storm, and the train sent to rescue them was blown off the tracks.
Okeechobee Hurricane: September 1928
Reaching category 5 strength when it slammed Puerto Rico, the storm then hit Palm Beach, Florida, with 150-mile-per-hour winds and little warning. Coastal residents were prepared, but 40 miles inland at Lake Okeechobee, the massive rainfall that accompanied the storm crumbled a six-foot-tall mud dike around the lake. The storm cost $100 million in damages and killed more than 1,800 people, although some estimates list the death toll as high as 4,000.
Florida Keys and Corpus Christi, Texas: September 1919
This was the only Atlantic hurricane to form in 1919, but it was a monster! With winds reaching 140 miles per hour, the category 4 storm originally made landfall in Key West, Florida, but continued over the warm waters of the Gulf of Mexico and struck again in Corpus Christi -- now downgraded to category 3, but with a 12-foot storm surge.
The storm cost more than $22 million in damages and killed between 600 and 900 people -- many of them passengers on ten ships lost in the Gulf of Mexico. Coincidentally, a boy named Bob Simpson survived the Corpus Christi leg of the storm, sparking his interest in hurricanes and eventually leading him to codevelop the Saffir-Simpson scale used to measure hurricane strength.
Galveston, Texas: September 1900
Climatologist Isaac Cline dismissed the notion that a hurricane could devastate the island city of Galveston, but when he noticed unusually heavy swells from the southeast, he drove his horse and buggy along the beach warning people to move to the mainland. Unfortunately, Cline's initially cavalier attitude about the storm may have played a part in the huge loss of life -- between 8,000 and 12,000 deaths -- because less than half the population evacuated and some people came from Houston just to watch.
The U.S. Weather Bureau ranked the storm a category 4 hurricane with wind speeds measured at 100 miles per hour before the measuring device blew away. Other records say winds peaked around 145 miles per hour. The hurricane wiped out about three-quarters of the city and caused nearly $20 million in damages.
These massive clouds form when wildfires give off heat. HowStuffWorks looks at how climate change is making conditions favorable for more to form.