This report describes the typical weather at the Salt Lake City International Airport (Salt Lake City, Utah, 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.
Salt Lake City, Utah has a cold semi-arid steppe climate. The area within 25 mi of this station is covered by lakes and rivers (29%), forests (23%), grasslands (19%), shrublands (13%), and croplands (10%).
The month of December is characterized by falling daily high temperatures, with daily highs ranging from 42°F to 35°F over the course of the month, exceeding 54°F or dropping below 25°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 22 with 9:14 hours of daylight; the longest day is December 1 with 9:28 hours of daylight.
The earliest sunrise is at 7:33am on December 1; the latest sunset is at 5:11pm on December 31; the latest sunrise is at 7:52am on December 30; the earliest sunset is at 5:00pm 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 ranges from 78% (partly cloudy) to 87% (mostly cloudy). The trend is for the sky to be becoming cloudier with the median cloud cover increasing by 8% from the start to the end of the month.
On December 16, a representative day, the sky is clear or mostly clear 24% of the time, partly cloudy 20% of the time, and mostly cloudy or overcast 55% of the time.
The probability that precipitation will be observed at this location varies throughout the month. Precipitation is most likely around December 31, occurring in 50% of days. Precipitation is least likely around December 1, occurring in 42% of days.
Throughout December, the most common forms of precipitation are light snow, moderate snow, and light rain.
Light snow is the most severe precipitation observed during 42% of those days with precipitation. It is most likely around December 31, when it is observed during 22% of all days.
Moderate snow is the most severe precipitation observed during 30% of those days with precipitation. It is most likely around December 29, when it is observed during 16% of all days.
Light rain is the most severe precipitation observed during 14% of those days with precipitation. It is most likely around December 1, when it is observed during 8% of all days.
The likelihood of snow falling is highest around December 31, occurring in 41% of days.
Accumulation at this location in December is just more likely than not. The chances of there being snow on the ground are highest around December 31, occurring 60% of the time.
The snow is typically at its deepest on December 31, with a median depth of 2.8"; the depth exceeds 6.6" only one year out of ten.
The relative humidity typically ranges from 50% (comfortable) to 90% (very humid) over the course of a typical December, rarely dropping below 33% (comfortable) and reaching as high as 98% (very humid).
The air is driest around December 1, at which time the relative humidity drops below 58% (mildly humid) three days out of four; it is most humid around December 27, rising above 86% (very 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 16°F (dry) to 30°F (dry) and is rarely below 6°F (dry) or above 37°F (dry).
Over the course of December typical wind speeds vary from 0 mph to 13 mph (calm to moderate breeze), rarely exceeding 23 mph (fresh breeze).
The highest average wind speed of 8 mph (gentle breeze) occurs around December 1, at which time the average daily maximum wind speed is 13 mph (moderate breeze).
The lowest average wind speed of 7 mph (light breeze) occurs around December 28, at which time the average daily maximum wind speed is 12 mph (gentle breeze).