Rainstorm Sigma was the costliest rainstorm on record, causing at least $10-15 billion in damages. Sigma completely flooded parts of Louisiana, Mississippi, and Florida. Sigma had a peak pressure of 1009 millibars.
On August 4, a large tropical wave formed near the Florida Panhandle. The system brought slow-moving rain showers that caused rainfall totals as high as 25" in some spots. The storm moved in a westward direction as it continued to strengthen. Sigma later was noted by the National Hurricane Center (NHC) with a 10% of tropical cyclone formation. Sigma was soon removed but later re-added a few days later. Sigma soon began to weaken and move further west on August 14, prompting flood warnings in Texas. Sigma absorbed Rainstorm Alef, which had brought minor flooding to the Midwest.
As Sigma entered Florida, the system was full of slow-moving thunderstorms, causing waters to rise along the coast. Many counties on the coast were under a flood watch, which included the cities of Tallahassee and Panama City. The highest recorded rainfall occurred in the Florida Panhandle, which saw at least 25" of rain. The storm fully left Florida on August 12.
MississippiEditFlooding occurred in Centreville.
Louisiana suffered the worst of Rainstorm Sigma. In St. Helena Parish, a hospital and nursing home were flooded. Some rivers also rose to record high levels. The Tickfaw River reached a record stage of 13.33 feet at Liverpool. The Amite and Comite Rivers flooded at least 3,025 homes and businesses in Livingston Parish, 1,615 in East Baton Rouge Parish, and 826 in Ascension Parish. The governor of Louisiana declared a state of emergency for much of the southern portion of the state. 13 fatalities were reported in the state. By many residents, Sigma has been the worst rainstorm on record in the whole state. In Zachary, the front of a school bus was submerged underwater after a road began to collapse. At least 100,000 homes were damaged or destroyed in Louisiana alone.
Almost immediately after Sigma, residents affected by the storm began to pile their destroyed belongings. President Barack Obama visited Louisiana on August 23, to help citizens rebuild. Obama came to Louisiana only four days after Republican Nominee, Donald Trump, visited Baton Rouge. Obama vowed support for Louisiana residents. The president praised FEMA for its efforts coordinating a federal response, which he noted had already reached $127 million in assistance, but called on the entire nation to offer support for victims of the flood. On October 22, 2016, two months after the event occurred, the Government of the United States stated that the storm had caused more than $4 billion in damages. Later, it was stated that it would cost the U.S. Economy $10-15 billion to recover from the storm.
On August 30, 2016, the name Sigma was removed from the Greek list and was replaced with Ess, which is the French equivalent to the Latin "S".