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.All weather events are affected by climate change because the environment in which they occur is warmer and moister than it used to be." One factor contributing to the storm's strength was abnormally warm sea surface temperatures offshore the East Coast of the United States—more than 3 °C (5 °F) above normal, to which global warming had contributed 0.6 °C (1 °F).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, causing it to double back on itself off the East Coast. In preparation of the storm, many residents stocked up on supplies and reinforced roofing material.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.
Government officials shut down schools, government buildings, and the airport in Kingston on the day prior to the arrival of Sandy.
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 billion (2012 USD) in damage.
President Barack Obama canceled a campaign stop with former President Bill Clinton in Virginia scheduled for October 29, as well as a trip to Colorado Springs, Colorado, the next day because of the impending storm. By the following day, Smith Island residents were evacuated with the assistance of the Maryland Natural Resources Police, Dorchester County opened two shelters for those in flood prone areas, and Ocean City initiated Phase I of their Emergency Operations Plan.
Officials warned that more than a hundred million tons of dirty sediment mixed with tree limbs and debris floating behind Conowingo Dam could be eventually poured into the Chesapeake Bay, posing a potential environmental threat.