This report describes the typical weather at the New York City (New York, United States) weather station over the course of an average December. It is based on the historical records from 1974 to 2012. Earlier records are either unavailable or unreliable.
New York, New York has a humid continental climate with hot summers and no dry season. The area within 25 mi of this station is covered by built-up areas (48%), oceans and seas (22%), forests (16%), grasslands (7%), and lakes and rivers (5%).
The month of December is characterized by falling daily high temperatures, with daily highs decreasing from 48°F to 41°F over the course of the month, exceeding 59°F or dropping below 29°F only one day in ten.
Over the course of December, the length of the day is essentially constant. The shortest day of the month is December 25 with 9:14 hours of daylight; the longest day is December 1 with 9:28 hours of daylight.
The earliest sunrise is at 7:01am on December 1; the latest sunset is at 4:38pm on December 31; the latest sunrise is at 7:20am on December 30; the earliest sunset is at 4:28pm on December 7.
Daylight savings time is observed in 2012 but it neither starts nor ends in December, so the entire month is in standard time.
The median cloud cover is 77% (partly cloudy) and does not vary substantially over the course of the month.
On December 16, a representative day, the sky is clear or mostly clear 31% of the time, partly cloudy 12% of the time, and mostly cloudy or overcast 49% of the time.
The average probability that some form of precipitation will be observed in a given day is 44%, with little variation over the course of the month.
Throughout December, the most common forms of precipitation are light rain, light snow, and moderate rain.
Light rain is the most severe precipitation observed during 32% of those days with precipitation. It is most likely around December 2, when it is observed during 17% of all days.
Light snow is the most severe precipitation observed during 24% of those days with precipitation. It is most likely around December 31, when it is observed during 15% of all days.
Moderate rain is the most severe precipitation observed during 21% of those days with precipitation. It is most likely around December 1, when it is observed during 11% of all days.
The likelihood of snow falling is highest around December 31, occurring in 22% of days.
Accumulation at this location in December is unlikely. The chances of there being snow on the ground are highest around December 31, occurring 12% of the time.
The snow is typically at its deepest on December 1, with a median depth of 3.9"; the depth exceeds 4.2" only one year out of ten.
The relative humidity typically ranges from 49% (comfortable) to 82% (humid) over the course of a typical December, rarely dropping below 32% (comfortable) and reaching as high as 100% (very humid).
The air is driest around December 12, at which time the relative humidity drops below 57% (mildly humid) three days out of four; it is most humid around December 1, rising above 70% (humid) three days out of four.
Dew point is often a better measure of how comfortable a person will find the weather than relative humidity because it more directly relates to whether perspiration will evaporate from the skin, thereby cooling the body. Lower dew points feel drier and higher dew points feel more humid.
Over the course of a typical December, the dew point typically varies from 15°F (dry) to 37°F (dry) and is rarely below -0°F (dry) or above 54°F (very comfortable).
Over the course of December typical wind speeds vary from 0 mph to 16 mph (calm to moderate breeze), rarely exceeding 24 mph (strong breeze).
The highest average wind speed of 9 mph (gentle breeze) occurs around December 31, at which time the average daily maximum wind speed is 15 mph (moderate breeze).
The lowest average wind speed of 9 mph (gentle breeze) occurs around December 2, at which time the average daily maximum wind speed is 15 mph (moderate breeze).