This report describes the typical weather at the Miami International Airport (Miami, Florida, 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.
Miami, Florida has a tropical monsoon climate with short dry season. The area within 25 mi of this station is covered by marshes (37%), oceans and seas (32%), built-up areas (13%), grasslands (11%), and croplands (6%).
The month of December is characterized by gradually falling daily high temperatures, with daily highs around 77°F throughout the month, exceeding 83°F or dropping below 67°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 21 with 10:32 hours of daylight; the longest day is December 1 with 10:39 hours of daylight.
The earliest sunrise is at 6:51am on December 1; the latest sunset is at 5:41pm on December 31; the latest sunrise is at 7:08am on December 31; the earliest sunset is at 5:30pm on December 4.
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 52% (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 41% of the time, partly cloudy 25% of the time, and mostly cloudy or overcast 35% of the time.
The average probability that some form of precipitation will be observed in a given day is 34%, with little variation over the course of the month.
Throughout December, the most common forms of precipitation are light rain and moderate rain.
Light rain is the most severe precipitation observed during 48% of those days with precipitation. It is most likely around December 6, when it is observed during 17% of all days.
Moderate rain is the most severe precipitation observed during 36% of those days with precipitation. It is most likely around December 19, when it is observed during 12% of all days.
Either snow is exceptionally unlikely to fall at this location in December or this station does not reliably report precipitation types.
The relative humidity typically ranges from 55% (mildly humid) to 89% (very humid) over the course of a typical December, rarely dropping below 40% (comfortable) and reaching as high as 98% (very humid).
The air is driest around December 12, at which time the relative humidity drops below 63% (mildly humid) three days out of four; it is most humid around December 31, rising above 85% (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 54°F (very comfortable) to 67°F (muggy) and is rarely below 38°F (dry) or above 74°F (very muggy).
The time of the month between December 10 and December 31 is the most comfortable, with dew points that are neither too dry nor too muggy.
Over the course of December typical wind speeds vary from 3 mph to 15 mph (light air to moderate breeze), rarely exceeding 21 mph (fresh breeze).
The highest average wind speed of 9 mph (gentle breeze) occurs around December 4, 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 10, at which time the average daily maximum wind speed is 15 mph (moderate breeze).