This report describes the typical weather at the King Khalid International Airport (Riyadh, Saudi Arabia) weather station over the course of an average January. It is based on the historical records from 1984 to 2012. Earlier records are either unavailable or unreliable.
Riyadh has a hot desert climate. The area within 25 mi of this station is covered by shrublands (70%), built-up areas (18%), and lakes and rivers (12%).
The month of January is characterized by essentially constant daily high temperatures, with daily highs around 68°F throughout the month, exceeding 80°F or dropping below 58°F only one day in ten.
Over the course of January, the length of the day is essentially constant. The shortest day of the month is January 1 with 10:37 hours of daylight; the longest day is January 31 with 11:01 hours of daylight.
The earliest sunrise is at 6:36am on January 31; the latest sunset is at 5:37pm on January 31; the latest sunrise is at 6:40am on January 15; the earliest sunset is at 5:15pm on January 1.
Daylight saving time (DST) is not observed in 2012.
The median cloud cover ranges from 10% (clear) to 15% (mostly clear).
On January 16, a representative day, the sky is clear or mostly clear 55% of the time, partly cloudy 13% of the time, and mostly cloudy or overcast 9% of the time.
The average probability that some form of precipitation will be observed in a given day is 12%, with little variation over the course of the month.
Throughout January, the most common forms of precipitation are moderate rain, thunderstorms, drizzle, and light rain.
Moderate rain is the most severe precipitation observed during 49% of those days with precipitation. It is most likely around January 1, when it is observed during 6% of all days.
Thunderstorms are the most severe precipitation observed during 22% of those days with precipitation. They are most likely around January 6, when it is observed during 3% of all days.
Drizzle is the most severe precipitation observed during 13% of those days with precipitation. It is most likely around January 6, when it is observed during 2% of all days.
Light rain is the most severe precipitation observed during 13% of those days with precipitation. It is most likely around January 4, when it is observed during 2% of all days.
Either snow is exceptionally unlikely to fall at this location in January or this station does not reliably report precipitation types.
The relative humidity typically ranges from 26% (dry) to 70% (humid) over the course of a typical January, rarely dropping below 13% (very dry), or exceeding 94% (very humid).
The air is driest around January 31, at which time the relative humidity drops below 31% (comfortable) three days out of four; it is most humid around January 4, rising above 57% (mildly 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 January, the dew point typically varies from 27°F (dry) to 41°F (dry) and is rarely below 13°F (dry) or above 53°F (very comfortable).
Over the course of January typical wind speeds vary from 0 mph to 13 mph (calm to moderate breeze), rarely exceeding 19 mph (fresh breeze).
The highest average wind speed of 7 mph (light breeze) occurs around January 31, at which time the average daily maximum wind speed is 13 mph (moderate breeze).
The lowest average wind speed of 6 mph (light breeze) occurs around January 1, at which time the average daily maximum wind speed is 11 mph (gentle breeze).