This report describes the typical weather at the Pittsburgh International Airport (Pittsburgh, Pennsylvania, 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.
Pittsburgh, Pennsylvania has a humid continental climate with hot summers and no dry season. The area within 25 mi of this station is covered by forests (78%) and built-up areas (19%).
The month of April is characterized by rapidly rising daily high temperatures, with daily highs increasing from 56°F to 66°F over the course of the month, exceeding 79°F or dropping below 41°F only one day in ten.
Over the course of April, the length of the day is increasing. From the start to the end of the month, the length of the day increases by 1:13 hours, implying an average day-over-day increase of 2.4 minutes.
The shortest day of the month is April 1 with 12:42 hours of daylight; the longest day is April 30 with 13:55 hours of daylight.
The earliest sunrise is at 6:20am on April 30; the latest sunset is at 8:16pm on April 30; the latest sunrise is at 7:04am on April 1; the earliest sunset is at 7:46pm on April 1.
Daylight savings time is observed in 2012 but it neither starts nor ends in April, so the entire month is in daylight time.
The median cloud cover ranges from 84% (mostly cloudy) to 89% (mostly cloudy). The trend is for the sky to be clearing with the median cloud cover decreasing by 6% from the start to the end of the month.
On April 15, a representative day, the sky is clear or mostly clear 26% of the time, partly cloudy 16% of the time, and mostly cloudy or overcast 58% of the time.
The probability that precipitation will be observed at this location varies throughout the month. Precipitation is most likely around April 1, occurring in 60% of days. Precipitation is least likely around April 30, occurring in 55% of days.
Throughout April, the most common forms of precipitation are light rain, moderate rain, light snow, and thunderstorms.
Light rain is the most severe precipitation observed during 34% of those days with precipitation. It is most likely around April 22, when it is observed during 21% of all days.
Moderate rain is the most severe precipitation observed during 21% of those days with precipitation. It is most likely around April 29, when it is observed during 13% of all days.
Light snow is the most severe precipitation observed during 18% of those days with precipitation. It is most likely around April 1, when it is observed during 17% of all days.
Thunderstorms are the most severe precipitation observed during 16% of those days with precipitation. They are most likely around April 30, when it is observed during 12% of all days.
The likelihood of snow falling is highest around April 1, occurring in 23% of days.
Either snow rarely accumulates at this location in April or snow depth measurements are unavailable or unreliable.
The relative humidity typically ranges from 39% (comfortable) to 83% (humid) over the course of a typical April, rarely dropping below 22% (dry) and reaching as high as 99% (very humid).
The air is driest around April 20, at which time the relative humidity drops below 47% (comfortable) three days out of four; it is most humid around April 30, rising above 75% (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 April, the dew point typically varies from 25°F (dry) to 47°F (dry) and is rarely below 12°F (dry) or above 59°F (comfortable).
Over the course of April typical wind speeds vary from 0 mph to 17 mph (calm to moderate breeze), rarely exceeding 25 mph (strong breeze).
The highest average wind speed of 10 mph (gentle breeze) occurs around April 7, at which time the average daily maximum wind speed is 17 mph (moderate breeze).
The lowest average wind speed of 9 mph (gentle breeze) occurs around April 28, at which time the average daily maximum wind speed is 16 mph (moderate breeze).