This report describes the typical weather at the General Rafael Buelna International Airport (Mazatlán, Mexico) weather station over the course of an average December. It is based on the historical records from 1990 to 2012. Earlier records are either unavailable or unreliable.
Mazatlán has a tropical savanna climate with dry winters. The area within 25 mi of this station is covered by forests (54%), oceans and seas (40%), and lakes and rivers (3%).
The month of December is characterized by gradually falling daily high temperatures, with daily highs around 82°F throughout the month, exceeding 87°F or dropping below 76°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 23 with 10:43 hours of daylight; the longest day is December 1 with 10:48 hours of daylight.
The earliest sunrise is at 6:30am on December 1; the latest sunset is at 5:31pm on December 31; the latest sunrise is at 6:46am on December 31; the earliest sunset is at 5:19pm on December 1.
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 20% (mostly clear) to 28% (mostly clear). 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 40% of the time, partly cloudy 11% of the time, and mostly cloudy or overcast 20% of the time.
The average probability that some form of precipitation will be observed in a given day is 7%, with little variation over the course of the month.
Throughout December, the most common forms of precipitation are light rain, moderate rain, and thunderstorms.
Light rain is the most severe precipitation observed during 49% of those days with precipitation. It is most likely around December 4, when it is observed during 4% of all days.
Moderate rain is the most severe precipitation observed during 27% of those days with precipitation. It is most likely around December 1, when it is observed during 2% of all days.
Thunderstorms are the most severe precipitation observed during 14% of those days with precipitation. They are most likely around December 1, when it is observed during 2% 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 44% (comfortable) to 89% (very humid) over the course of a typical December, rarely dropping below 33% (comfortable) and reaching as high as 95% (very humid).
The air is driest around December 30, at which time the relative humidity drops below 50% (comfortable) three days out of four; it is most humid around December 1, rising above 84% (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 49°F (dry) to 65°F (mildy humid) and is rarely below 41°F (dry) or above 70°F (muggy).
The time of the month between December 1 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 0 mph to 11 mph (calm to gentle breeze), rarely exceeding 18 mph (fresh breeze).
The highest average wind speed of 5 mph (light breeze) occurs around December 19, at which time the average daily maximum wind speed is 11 mph (gentle breeze).
The lowest average wind speed of 5 mph (light breeze) occurs around December 1, at which time the average daily maximum wind speed is 11 mph (gentle breeze).