Climate of New York City

According to the Köppen climate classification, the climate of New York City is humid subtropical (Cfa), with parts of the city transitioning into a humid continental climate. (Dfa).^[1] The city experiences long, hot, humid summers with frequent late day thundershowers, and moderately cold winters, with occasional snow or a mix of snow and rain. As it is much more geographically southern, it is usually warmer in winter than in Upstate New York. Also, New York's enormous population, human activity, and vast amounts of large buildings and streets, which absorb sunlight during the day, contribute significantly to the urban heat island effect.

Meteorological records have been kept at Central Park since 1821, although the station was relocated to a different part of the park on January 1, 1920.^[2] There are also other weather stations in the area including one at LaGuardia Airport, beginning in 1940, and at JFK Airport, beginning in 1948. However, due to Central Park's long records and central location, it is often considered the main station for the city. Hence, all records unless otherwise stated will be for this station.

The highest temperature ever observed in Central Park is 106 °F (41 °C) on July 9, 1936 - although LaGuardia reported 107 °F (42 °C) on July 3, 1966, and the lowest is −15 °F (−26 °C) on February 9, 1934. The lowest daily maximum is 2 °F (−17 °C) on December 30, 1917. The highest daily minimum at Central Park is 87 °F (31 °C) on July 2, 1903.^[3]

The averages 42 to 49 inches of precipitation annually, with snowfall averaging29.8 in (75.7 cm) per year but is highly variable between winter seasons.^[4] The city can also be prone to strong winds, being a coastal location it is exposed to the Atlantic. Hurricane Hazel in 1954 produced a wind gust of 83 mph, while a gust of 78 miles per hour (126 km/h) being reported on December 2, 1974.^[5] Governors Island, Manhattan, in New York Harbor, is planned to host a US$1 billion research and education center poised to make New York City the global leader in addressing the climate crisis.^[6]

New York City falls under different climate types depending on the climate classification system used. However, the Köppen climate classification system is the most widely used climate classification scheme, in which New York City falls under the humid subtropical zone.

In the Holdridge life zones system, having a mean annual biotemperature above 53.6 °F (12 °C) and mean annual precipitation above 39.4 inches (1,000 mm), New York City features a warm temperate moist forest climate.^[12] By the Trewartha classification, the city is defined as having a Temperate climate (Dc).^[13][14] Annually, the city averages 234 days with at least some sunshine.^[15] The USDA plant hardiness zones are 7a and 7b. Most of the city is found in 7b, with forested areas and parks being in 7a, as shown in Staten Island and suburban areas. The city also has some small densely populated areas in 8a, like around Laguardia airport.^[16]

The city's annual temperature profile consists of a warm to hot season from May through October, and a cool to cold period from November through April. However, due to its proximity to the Atlantic Ocean, these swings are less significant than areas further inland. The Atlantic serves as a moderator of the temperature meaning the city is milder than areas inland during the winter and cooler during the summer. All extremes are for the Central Park station.

New York City averages 49.9 in (1,267 mm) annually. Spring is the wettest season. February is the driest month. Every single month in the city's recorded history has reported some rainfall, showing the variability of the climate. On occasion, tropical systems can drop heavy rainfall. The record for days without rain, is 36 consecutive days, between October 10 and November 13, 1924.^[23] The most rainfall in 24 hours was 8.28 in (210.3 mm) on September 23, 1882.^[24]

In winter, on occasion, the city can see snow. Annually, most snow in New York City occurs from December through late March. Snowfall averages 29.8 in (75.7 cm) per year but is highly variable between winter seasons.^[25] The most snowfall was 27.3 in (69 cm) on January 23, 2016.^[24]

Being a coastal city, New York City is expected to experience significant effects from rising sea levels. Predictions that the sea level will rise by as much as 6 feet (1.8 m) by 2100 have prompted the city's mayor to invest $10 billion into keeping the city safe.^[32] The city is also expected to become more susceptible to storm surges and flooding, meaning events like Hurricane Sandy's impacts will become more likely in the future.

Time series plot for Central Park, 1869–present

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