This report describes the typical weather at the Tucson International Airport (Tucson, Arizona, United States) weather station over the course of an average April. 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 April is characterized by rising daily high temperatures, with daily highs increasing from 77°F to 86°F over the course of the month, exceeding 94°F or dropping below 65°F only one day in ten.
Over the course of April, the length of the day is gradually increasing. From the start to the end of the month, the length of the day increases by 54 minutes, implying an average day-over-day increase of 1.8 minutes.
The shortest day of the month is April 1 with 12:33 hours of daylight; the longest day is April 30 with 13:26 hours of daylight.
The earliest sunrise is at 5:38am on April 30; the latest sunset is at 7:04pm on April 30; the latest sunrise is at 6:11am on April 1; the earliest sunset is at 6:44pm on April 1.
Daylight savings time (DST) is not observed in 2012.
The median cloud cover is 2% (clear) and does not vary substantially over the course of the month.
On April 15, a representative day, the sky is clear or mostly clear 74% of the time, partly cloudy 10% of the time, and mostly cloudy or overcast 15% of the time.
The average probability that some form of precipitation will be observed in a given day is 10%, with little variation over the course of the month.
Throughout April, the most common forms of precipitation are light rain, thunderstorms, and moderate rain.
Light rain is the most severe precipitation observed during 41% of those days with precipitation. It is most likely around April 1, when it is observed during 6% of all days.
Thunderstorms are the most severe precipitation observed during 27% of those days with precipitation. They are most likely around April 30, when it is observed during 4% of all days.
Moderate rain is the most severe precipitation observed during 23% of those days with precipitation. It is most likely around April 1, when it is observed during 3% of all days.
Either snow is exceptionally unlikely to fall at this location in April or this station does not reliably report precipitation types.
The relative humidity typically ranges from 12% (very dry) to 57% (mildly humid) over the course of a typical April, rarely dropping below 6% (very dry) and reaching as high as 96% (very humid).
The air is driest around April 30, at which time the relative humidity drops below 14% (very dry) three days out of four; it is most humid around April 1, rising above 37% (comfortable) 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 April, the dew point typically varies from 19°F (dry) to 35°F (dry) and is rarely below 7°F (dry) or above 46°F (dry).
Over the course of April typical wind speeds vary from 0 mph to 16 mph (calm to moderate breeze), rarely exceeding 23 mph (fresh breeze).
The highest average wind speed of 9 mph (gentle breeze) occurs around April 30, at which time the average daily maximum wind speed is 16 mph (moderate breeze).
The lowest average wind speed of 8 mph (gentle breeze) occurs around April 13, at which time the average daily maximum wind speed is 16 mph (moderate breeze).