Hurricane Sandy (unofficially referred to as Superstorm Sandy) was an extremely large and devastating tropical cyclone which ravaged the Caribbean and the coastal Mid-Atlantic region of the United States in late October 2012. It was the largest Atlantic hurricane on record as measured by diameter, with tropical-storm-force winds spanning 1,150 miles (1,850 km). The storm inflicted nearly US$70 billion in damage (equivalent to $98 billion in 2025), and killed 254 people in eight countries, from the Caribbean to Canada. The eighteenth named storm, tenth hurricane, and second major hurricane of the 2012 Atlantic hurricane season, Sandy was a Category 3 storm at its peak intensity when it made landfall in Cuba, though most of the damage it caused was after it became a Category 1–equivalent extratropical cyclone off the coast of the Northeastern United States.
Sandy developed from a tropical wave in the western Caribbean Sea on October 22, quickly strengthened, and was upgraded to Tropical Storm Sandy six hours later. Sandy moved slowly northward toward the Greater Antilles and gradually intensified. On October 24, Sandy became a hurricane, made landfall near Kingston, Jamaica, re-emerged a few hours later into the Caribbean Sea and strengthened into a Category 2 hurricane. On October 25, Sandy hit Cuba as a Category 3 hurricane, then weakened to a Category 1 hurricane. Early on October 26, Sandy moved through the Bahamas. On October 27, Sandy briefly weakened to a tropical storm and then strengthened back to a Category 1 hurricane. Early on October 29, Sandy curved west-northwest (the "left turn" or "left hook") and then moved ashore near Brigantine, New Jersey, just to the northeast of Atlantic City, as a post-tropical cyclone with hurricane-force winds. Sandy continued drifting inland for another few days while gradually weakening, until it was absorbed by another approaching extratropical storm on November 2.
In Jamaica, winds left 70% of residents without electricity, blew roofs off buildings, killed one person, and caused about $100 million (equivalent to $140 million in 2025) in damage. Sandy's outer bands brought flooding to Haiti, killing a total of 75 people, causing food shortages, and leaving about 200,000 homeless; the hurricane also caused two deaths in the Dominican Republic. In Puerto Rico, one man was swept away by a swollen river. In Cuba, there was extensive coastal flooding and wind damage inland, destroying some 15,000 homes, killing 11, and causing $2 billion (equivalent to $2.8 billion in 2025) in damage. Sandy caused two deaths and an estimated $700 million (equivalent to $982 million in 2025) in damage in the Bahamas.
In the United States, Hurricane Sandy affected 24 states, including the entire eastern seaboard from Florida to Maine and west across the Appalachian Mountains to Michigan and Wisconsin, with particularly severe damage in New Jersey and New York. Its storm surge hit New York City on October 29, flooding streets, tunnels and subway lines and cutting power in and around the city. Damage in the United States amounted to $65 billion (equivalent to $91 billion in 2025). In Canada, two were killed in Ontario, and the storm caused an estimated C$100 million (equivalent to C$135 million in 2025) in damage throughout Ontario and Quebec.
Hurricane Sandy (unofficially referred to as Superstorm Sandy) was an extremely large and devastating tropical cyclone which ravaged the Caribbean and the coastal Mid-Atlantic region of the United States in late October 2012. It was the largest Atlantic hurricane on record as measured by diameter, with tropical storm-force winds spanning 1,150 miles (1,850 km). The storm inflicted nearly US$70 billion in damage (equivalent to $98 billion in 2025), and killed 254 people in eight countries, from the Caribbean to Canada. The eighteenth named storm, tenth hurricane, and second major hurricane of the 2012 Atlantic hurricane season, Sandy was a Category 3 storm at its peak intensity when it made landfall in Cuba, though most of the damage it caused was after it became a Category 1–equivalent extratropical cyclone off the coast of the Northeastern United States.
Sandy developed from a tropical wave in the western Caribbean Sea on October 22, quickly strengthened, and was upgraded to Tropical Storm Sandy six hours later. Sandy moved slowly northward toward the Greater Antilles and gradually intensified. On October 24, Sandy became a hurricane, made landfall near Kingston, Jamaica, re-emerged a few hours later into the Caribbean Sea and strengthened into a Category 2 hurricane. On October 25, Sandy hit Cuba as a Category 3 hurricane, then weakened to a Category 1 hurricane. Early on October 26, Sandy moved through the Bahamas. On October 27, Sandy briefly weakened to a tropical storm and then strengthened back to a Category 1 hurricane. Early on October 29, Sandy curved west-northwest (the "left turn" or "left hook") and then moved ashore near Brigantine, New Jersey, just to the northeast of Atlantic City, as a post-tropical cyclone with hurricane-force winds. Sandy continued drifting inland for another few days while gradually weakening, until it was absorbed by another approaching extratropical storm on November 2.
In Jamaica, winds left 70% of residents without electricity, blew roofs off buildings, killed one person, and caused about $100 million (equivalent to $140 million in 2025) in damage. Sandy's outer bands brought flooding to Haiti, killing a total of 75 people, causing food shortages, and leaving about 200,000 homeless; the hurricane also caused two deaths in the Dominican Republic. In Puerto Rico, one man was swept away by a swollen river. In Cuba, there was extensive coastal flooding and wind damage inland, destroying some 15,000 homes, killing 11, and causing $2 billion (equivalent to $2.8 billion in 2025) in damage. Sandy caused two deaths and an estimated $700 million (equivalent to $982 million in 2025) in damage in the Bahamas.
In the United States, Hurricane Sandy affected 24 states, including the entire eastern seaboard from Florida to Maine and west across the Appalachian Mountains to Michigan and Wisconsin, with particularly severe damage in New Jersey and New York. Its storm surge hit New York City on October 29, flooding streets, tunnels and subway lines and cutting power in and around the city. Damage in the United States amounted to $65 billion (equivalent to $91 billion in 2025). In Canada, two were killed in Ontario, and the storm caused an estimated C$100 million (equivalent to C$135 million in 2025) in damage throughout Ontario and Quebec.
Meteorological history
Hurricane Sandy began as a low-pressure system which developed sufficient organized convection to be classified as Tropical Depression Eighteen on October 22 south of Kingston, Jamaica. It moved slowly at first due to a ridge to the north. Low wind shear and warm waters allowed for strengthening, and the system was named Tropical Storm Sandy late on October 22. Early on October 24, an eye began developing, and it was moving steadily northward due to an approaching trough. Later that day, the National Hurricane Center (NHC) upgraded Sandy to hurricane status about 65 mi (105 km) south of Kingston. At about 1900 UTC that day, Sandy made landfall near Kingston with winds of about 85 mph (137 km/h). Just offshore of Cuba, Sandy rapidly intensified to a Category 3 hurricane, with sustained winds at 115 mph (185 km/h) and a minimum central pressure of 954 millibars (28.2 inHg), and at that intensity, Sandy made landfall just west of Santiago de Cuba at 0525 UTC on October 25. Operationally, Sandy was assessed to have peaked as a high-end Category 2 hurricane, with maximum sustained winds of 110 mph (180 km/h).
After Sandy exited Cuba, the structure of the storm became disorganized, and it turned to the north-northwest over the Bahamas. By October 27, Sandy was no longer fully tropical, as evidenced by the development of frontal structures in its outer circulation. Despite strong shear, Sandy maintained its convection due to influence from an approaching trough; the same trough eventually turned the hurricane to the northeast. After briefly weakening to a tropical storm, Sandy re-intensified into a Category 1 hurricane, and on October 28 an eye began redeveloping. The storm moved around an upper-level low over the eastern United States and also to the southwest of a ridge over Atlantic Canada, turning it to the northwest.
Sandy briefly re-intensified to Category 2 intensity on the morning of October 29, by which time it had become an extremely large hurricane, with a record gale-force wind diameter of over 1,150 miles (1,850 km), and an unusually low central barometric pressure of 940 mbar, possibly due to the very large size of the system. This pressure set records as the lowest ever observed in many cities across the Northeastern United States. The convection diminished while the hurricane accelerated toward the New Jersey coast, and the cyclone was no longer tropical by 2100 UTC on October 29. About 2½ hours later, Sandy made landfall near Brigantine, New Jersey, with sustained winds of 80 mph (130 km/h). During the next four days, Sandy's remnants drifted northward and then northeastward over Ontario, before merging with another low-pressure area over Eastern Canada on November 2.
Forecasts
On October 23, 2012, the path of Hurricane Sandy was correctly predicted by the European Centre for Medium-Range Weather Forecasts (ECMWF) headquartered in Reading, England, nearly eight days in advance of its striking the American East Coast. The computer model noted that the storm would turn west towards land and strike the New York/New Jersey region on October 29, rather than turn east and head out to the open Atlantic as most hurricanes in this position do. By October 27, four days after the ECMWF made its prediction, the National Weather Service and National Hurricane Center confirmed the path of the hurricane predicted by the European model. The National Weather Service was criticized for not employing its higher-resolution forecast models the way that its European counterpart did. A subsequent hardware and software upgrade completed at the end of 2013 enabled the NWS to make predictions more accurately and farther in advance than the technology in 2012 had allowed.
Relation to global warming
According to NCAR senior climatologist Kevin E. Trenberth, "The answer to the oft-asked question of whether an event is caused by climate change is that it is the wrong question. All weather events are affected by climate change because the environment in which they occur is warmer and moister than it used to be." Although NOAA meteorologist Martin Hoerling attributes Sandy to "little more than the coincidental alignment of a tropical storm with an extratropical storm", Trenberth does agree that the storm was caused by "natural variability" but adds that it was "enhanced by global warming". One factor contributing to the storm's strength was abnormally warm sea surface temperatures offshore of the East Coast of the United States—more than 5 °F (3 °C) above normal, to which global warming had contributed 1 °F (0.6 °C). As the temperature of the atmosphere increases, the capacity to hold water increases, leading to stronger storms and higher rainfall amounts.
As they move north, Atlantic hurricanes typically are forced east and out to sea by the Prevailing Westerlies. In Sandy's case, this typical pattern was blocked by a ridge of high pressure over Greenland resulting in a negative North Atlantic Oscillation, forming a kink in the jet stream and causing it to double back on itself off the East Coast. Sandy was caught up in this southeasterly flow, taking the storm on an unusual northwest path. The blocking pattern over Greenland also stalled an Arctic front which combined with the cyclone. Mark Fischetti of Scientific American said that the jet stream's unusual shape was caused by the melting of Arctic ice. Trenberth said that while a negative North Atlantic Oscillation and a blocking anticyclone were in place, the null hypothesis remained that this was just the natural variability of weather. Sea level along the New York and New Jersey coasts has increased by nearly 12 inches (30 cm) over the last hundred years, which contributed to the storm surge. One group of scientists estimated that the anthropogenic (human activity-driven) climate change was responsible for approximately 3.5 inches (8.9 cm) of sea level rise in New York, which permitted additional storm surge that caused approximately $8.1 billion out of the $60 billion in reported economic damage and to an extension of the flood zone to impact approximately 71,000 more people than would have been the case without it. Harvard geologist Daniel P. Schrag calls Hurricane Sandy's 13-foot (4.0 m) storm surge an example of what will, by mid-century, be the "new norm on the Eastern seaboard".
Preparations
Caribbean and Bermuda
After the storm became a tropical cyclone on October 22, the Government of Jamaica issued a tropical storm watch for the entire island. Early on October 23, the watch was replaced with a tropical storm warning and a hurricane watch was issued. At 1500 UTC, the hurricane watch was upgraded to a hurricane warning, while the tropical storm warning was discontinued. In preparation of the storm, many residents stocked up on supplies and reinforced roofing material. Acting Prime Minister Peter Phillips urged people to take this storm seriously, and also to take care of their neighbors, especially the elderly, children, and disabled. Government officials shut down schools, government buildings, and the airport in Kingston on the day prior to the arrival of Sandy. Meanwhile, numerous and early curfews were put in place to protect residents, properties, and to prevent crime. Shortly after Jamaica issued its first watch on October 22, the Government of Haiti issued a tropical storm watch for Haiti. By late October 23, it was modified to a tropical storm warning.
At 1515 UTC on October 26, the Bermuda Weather Service issued a tropical storm watch for Bermuda, reflecting the enormous size of the storm and the anticipated wide-reaching impacts.
United States
Much of the East Coast of the United States, in Mid-Atlantic and New England regions, had a good chance of receiving gale-force winds, flooding, heavy rain and possibly snow early in the week of October 28 from an unusual hybrid of Hurricane Sandy and a winter storm producing a Fujiwhara effect. Government weather forecasters said there was a 90% chance that the East Coast would be impacted by the storm. Jim Cisco of the Hydrometeorological Prediction Center coined the term "Frankenstorm", as Sandy was expected to merge with a storm front a few days before Halloween. As coverage continued, several media outlets began eschewing this term in favor of "superstorm". Utilities and governments along the East Coast attempted to head off long-term power failures Sandy might cause. Power companies from the Southeast to New England alerted independent contractors to be ready to help repair storm damaged equipment quickly and asked employees to cancel vacations and work longer hours. Researchers from Johns Hopkins University, using a computer model built on power outage data from previous hurricanes, conservatively forecast that 10 million customers along the Eastern Seaboard would lose power from the storm.
Through regional offices in Atlanta, Philadelphia, New York City, and Boston, the Federal Emergency Management Agency (FEMA) monitored Sandy, closely coordinating with state and tribal emergency management partners in Florida and the Southeast, Mid-Atlantic, and New England states. President Obama signed emergency declarations on October 28 for several states expected to be impacted by Sandy, allowing them to request federal aid and make additional preparations in advance of the storm. Flight cancellations and travel alerts on the U.S. East Coast were put in place in the Mid-Atlantic and the New England areas. Over 5,000 commercial airline flights scheduled for October 28 and 29 were canceled by the afternoon of October 28 and Amtrak canceled some services through October 29 in preparation for the storm. In addition, the National Guard and U.S. Air Force put as many as 45,000 personnel in at least seven states on alert for possible duty in response to the preparations and aftermath of Sandy.
Southeast
Schools on the Treasure Coast announced closures for October 26 in anticipation of Sandy.
At 0900 UTC on October 26, a tropical storm watch was issued from the mouth of the Savannah River in South Carolina to Oregon Inlet, North Carolina, including Pamlico Sound. Twelve hours later, the portion of the tropical storm watch from the Santee River in South Carolina to Duck, North Carolina, including Pamlico Sound, was upgraded to a warning. Governor of North CarolinaBeverly Perdue declared a state of emergency for 38 eastern counties on October 26, which took effect on the following day. By October 29, the state of emergency was extended to 24 counties in western North Carolina, with up to 12 in (30 cm) of snow attributed to Sandy anticipated in higher elevations. The National Park Service closed at least five sections of the Blue Ridge Parkway.