This report describes the typical weather at the Tucson International Airport (Tucson, Arizona, United States) weather station over the course of an average January. It is based on the historical records from 1974 to 2012. Earlier records are either unavailable or unreliable.
Tucson, Arizona has a hot semi-arid steppe climate. The area within 25 mi of this station is covered by shrublands (70%), grasslands (23%), forests (4%), and built-up areas (3%).
The month of January is characterized by gradually rising daily high temperatures, with daily highs around 65°F throughout the month, exceeding 76°F or dropping below 53°F only one day in ten.
Over the course of January, the length of the day is gradually increasing. The shortest day of the month is January 1 with 10:05 hours of daylight; the longest day is January 31 with 10:38 hours of daylight.
The earliest sunrise is at 7:18am on January 31; the latest sunset is at 5:56pm on January 31; the latest sunrise is at 7:26am on January 6; the earliest sunset is at 5:30pm on January 1.
Daylight savings time (DST) is not observed in 2012.
The median cloud cover is 7% (clear) and does not vary substantially over the course of the month.
On January 16, a representative day, the sky is clear or mostly clear 63% of the time, partly cloudy 10% of the time, and mostly cloudy or overcast 26% of the time.
The average probability that some form of precipitation will be observed in a given day is 20%, with little variation over the course of the month.
Throughout January, the most common forms of precipitation are light rain and moderate rain.
Light rain is the most severe precipitation observed during 51% of those days with precipitation. It is most likely around January 18, when it is observed during 11% of all days.
Moderate rain is the most severe precipitation observed during 32% of those days with precipitation. It is most likely around January 16, when it is observed during 7% 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 24% (dry) to 74% (humid) over the course of a typical January, rarely dropping below 10% (very dry) and reaching as high as 99% (very humid).
The air is driest around January 28, at which time the relative humidity drops below 31% (comfortable) three days out of four; it is most humid around January 1, rising above 59% (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 22°F (dry) to 35°F (dry) and is rarely below 9°F (dry) or above 47°F (dry).
Over the course of January typical wind speeds vary from 0 mph to 13 mph (calm to moderate breeze), rarely exceeding 22 mph (fresh breeze).
The highest average wind speed of 7 mph (light breeze) occurs around January 27, 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 January 1, at which time the average daily maximum wind speed is 12 mph (moderate breeze).