these events have happened in history before..this is not the first time NY has flooded, seen severe weather or snow from a extratropical/tropical systems-the rest of the years are in the link for viewing from wikipedia
between 1278 and 1438 — A major hurricane struck the modern-day New York/New Jersey area, probably the strongest in recent millennium.
August 25, 1635 — A hurricane that is reported to have tracked parallel to the East Coast impacts New England and New York, although it remains unknown if any damage occurred.
September 8, 1667 — A 'severe storm' is reported in Manhattan and is reported to be a continuation of a powerful hurricane which affected the Mid-Atlantic.
October 29, 1693 — The Great Storm of 1693 causes severe damage on Long Island, and is reported to create the Fire Island Cut as a result of the coast-changing storm surge and waves.
September 23, 1785 — Several large ships crash into Governors Island as a result of powerful waves which are reported to have been generated by a tropical cyclone.
August 19, 1788 — A hurricane strikes New York City or Long Island and is reported to have left the west side of the Battery "laid in ruins" after severe flooding occurs.
Estimated track of the 1821 Norfolk and Long Island hurricane
October 9, 1804 — Heavy snow falls in Eastern New York peaking at 30 inches (75 cm) as a hurricane tracks northward along the East Coast and becomes extratropical, as cold air fed into the system.
September 5, 1815 — A hurricane tracks over North Carolina and parallels the East Coast before producing a heavy rainstorm in New York.
September 24, 1815 — Several hundred trees fall and the majority of the fruit was stripped off apple trees just prior to harvesting time after a hurricane makes landfall on Long Island.
September 16, 1816 — A possible hurricane strikes New York City, but damage remains unknown.
August 9, 1817 — A tropical storm produces heavy rainfall in New York City and Long Island.
September 3, 1821 — The 1821 Norfolk and Long Island hurricane results in severe damage on Long Island and is accompanied by storm surge of 13 feet (4 m). High wind causes a ship to crash on Long Island killing 17 people.
June 4, 1825 — A hurricane moves off the East Coast and tracks south of New York causing several ship wrecks, and killing seven people.
August 27, 1827 — High tides are reported in New York City which are caused by a hurricane offshore.
August 1, 1830 – A hurricane passes to the east of New York and produces gale-force winds to New York City and Long Island.
October 4, 1841 — Gale–force winds affect New York City as a hurricane tracks north along the East Coast of the United States. Damage is estimated at $2 million (1841 USD, $41 million 2007 USD).
October 13, 1846 — The Great Havana Hurricane of 1846 tracks inland, causing some damage to New York City.
October 6, 1849 — Severe structural damage occurs in New York City and Long Island with the passage of a hurricane to the east.
July 19, 1850 — A hurricane destroys a Coney Island bath house and causes heavy rain, although damage is unknown. This storm destroyed the ship Elizabeth off Fire Island and drowned American transcendentalist Margaret Fuller.
August 24, 1850 — A storm that is reported to be a hurricane affects New York and New England although there is no known damage.
September 9, 1854 — A hurricane brushes the East Coast from Florida to New England causing rain on Long Island.
September 16, 1858 — Low barometric pressure of 28.87 inches mercury at Sag Harbor is reported, and is thought to be associated with a tropical cyclone which causes no known damage.
September 6, 1869 — A category 3 hurricane makes landfall in Rhode Island and brushes Long Island, which is affected by rain, although minimal damage resulted from the storm.
October 28, 1872 — A tropical storm passes over New York City and Long Island.
October 1, 1874 — New York City and the Hudson Valley receives rainfall after a minimal tropical storm tracked over Eastern New York.
September 19, 1876 — The remnants of the San Felipe hurricane track over western New York State, although damage is unknown.
October 24, 1878 — The state is affected by tropical storm-force winds and heavy rain with the passage of a hurricane, which made landfall in Virginia.
August 22, 1888 — A tropical storm tracks over New York City before tracking north along the East Coast of the United States.
August 24, 1893 — Hog Island is washed away by strong storm surge associated with a tropical storm of unknown strength. According to HURDAT, this was a Category 1 hurricane that struck the western end of the Rockaway Peninsula, passing through Brooklyn as a weakening hurricane. Manhattan Island saw gale force winds to 56 mph.
October 10, 1894 10 People were killed and 15 injured at 74 Monroe Street in Manhattan when winds blew a building under construction onto a tenement crushing it. Extensive damage in the NYC and Long Island to telegraph lines, trees and boats docked on shore. Storm formed over Gulf of Mexico as a Category 3 weakened over land in the Southeast and re strengthened to a Category 1 over the Chesapeake Bay before striking Long Island.
Storm surge from the 1938 New England hurricane
September 17, 1903 — The 1903 Vagabond Hurricane produces wind gusts in excess of 65 mph (105 km/h) and 3 inches (75 mm) of rain in Central Park.
August 15, 1904 — A Category 2 hurricane skirts the East Coast of the United States producing gale-force winds and heavy rain in Eastern New York and Long Island.
August 2, 1908 — A hurricane develops near North Carolina and moves northward along the coast, brushing Long Island.
July 21, 1916 — Strong winds are reported on Long Island as a category 3 hurricane passes to the east.
August 25, 1933 — The 1933 Chesapeake Potomac Hurricane produces up to 6 inches (150 mm) of rain in Southeast New York State; other damage is unknown.
September 8, 1934 — A strong tropical storm makes landfall on Long Island.
September 20, 1936 — Strong waves and storm surge associated with a powerful hurricane floods much of Long Beach Island and causes severe beach erosion along the coast.
September 21, 1938 — The New England Hurricane of 1938 (Also Called "The Long Island Express") makes landfall on Suffolk County (Long Island) as a category 3 hurricane on the Saffir-Simpson hurricane scale. Wind gusts of 125 mph (200 km/h) and storm surge of 18 feet (5 m) washes across part of the island. In New York 60 deaths and hundreds of injuries were attributed to the storm. In addition, 2,600 boats and 8,900 houses are destroyed. Throughout New England the hurricane killed over 682 people, damaged or destroyed over 57,000 homes, and caused property losses estimated at $4.7 billion (2005 US dollars).
September 14, 1944 — The 1944 Great Atlantic Hurricane makes landfall on Long Island as a category 1 hurricane on the Saffir-Simpson hurricane scale at a high forward speed of 40 mph (64 km/h). Wind gusts of well over 100 mph (160 km/h) breaks previous wind records in New York City, while a minimum pressure reading of 28.47 inches is recorded on Long Island. 117 homes are completely destroyed, while 2,427 are severely damaged and almost 1000 businesses are destroyed or damaged. In all, six people are killed, and one person is injured.
September 18, 1945 — A weak tropical depression crosses into Southeastern New York.
August 29, 1949 — A tropical storm tracks into Central New York causing no known damage.
Rainfall from Hurricane Agnes (1972)
1954 — Hurricane Hazel - wind gust of 113 mph at Battery Park, highest ever recorded in New York City.
August 31, 1954 — Hurricane Carol makes landfall on Long Island and produces wind gusts of 120 miles per hour (190 km/h) on Montauk Point. On eastern Long Island near where Carol made landfall, a pressure of 960 mbar is recorded. Winds on the island gust to 120 mph (195 km/h). The hurricane's storm surge covers the Montauk Highway in Montauk, effectively isolating eastern Long Island for a period of time. Due to the compact nature of the storm, most of Long Island is largely unaffected by the hurricane. Specific damage totals for New York are unknown, although the storm in its entirety causes $460 million (1954 USD) in damage.
September 10, 1954 — Hurricane Edna tracks to the east of Long Island producing 9 inches (230 mm) of rain. Prior to the storm, New York City orders an emergency standby for the majority of its hospitals, and subways.
August 13, 1955 — Hurricane Connie produces 13.24 inches (370 mm) of rain in Southeast New York, although damage is unknown.
September 28, 1956 — Hurricane Flossy tracks to the south of Long Island, brushing it with light rainfall.
October 1, 1959 — The remnants of Hurricane Gracie track into Central New York and drops up to 6 inches (150 mm) of rain.
September 11, 1960 — Hurricane Donna makes landfall on Long Island as a Category 2 hurricane. Sustained winds of 100 mph (160 km/h) on eastern Long Island and 70 mph (110 km/h) winds on western Long Island are reported, and tides are 6 feet (2 m) above normal along most of the coast. Strong waves also cause beach erosion and several homes along the shore to be destroyed. Due to well-executed warnings, damages are extremely low, and it is reported that no deaths result from the storm.
September 21, 1961 — Hurricane Esther causes $3 million (1961 USD, $20 million 2007 USD) in damage in Suffolk County as it tracks to the east of Long Island. Coastal areas of Long Island were flooded, as well as storm surge and wind gusts of 108 mph (173 km/h), which causes 260,000 homes to be left without power.
October 8, 1962 — Hurricane Daisy tracks east of New England, producing light rainfall in extreme eastern portions of Upstate New York.
September 23, 1964 — Beach erosion and moderate wind gusts are reported on Long Island as Hurricane Gladys tracks a couple hundred miles south of New York.
October 19, 1964 — Light rainfall is reported as Hurricane Isbell tracks off the coast.
September 10, 1969 — Rainfall up to 3 inches (75 mm) is reported on Long Island and in portions of Southeastern New York associated with Hurricane Gerda.
August 28, 1971 — Tropical Storm Doria produces up to 8 inches (200 mm) of rain in New York City and Upstate New York causing moderate to severe flooding and floods subways in New York City.
June 22, 1972 — Hurricane Agnes makes landfall near New York City and produces up to 12 inches (300 mm) of rain in Southeastern New York State and much of Western New York, with locally higher amounts. Storm tides of 3.1 feet (1 m) and wind gusts of 55 miles per hour (89 km/h) occur in New York City, and severe river flooding causes six deaths.
September 4, 1972 — Tropical Storm Carrie produces light rainfall on the eastern end of Long Island.