This report describes the typical weather at the Dane County Regional Airport (Madison, Wisconsin, 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.
Madison, Wisconsin has a humid continental climate with hot summers and no dry season. The area within 25 mi of this station is covered by grasslands (49%), croplands (45%), and lakes and rivers (3%).
The month of April is characterized by rapidly rising daily high temperatures, with daily highs increasing from 51Â°F to 63Â°F over the course of the month, exceeding 76Â°F or dropping below 36Â°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 1:20 hours, implying an average day-over-day increase of 2.7 minutes.
The shortest day of the month is April 1 with 12:46 hours of daylight; the longest day is April 30 with 14:06 hours of daylight.
The earliest sunrise is at 5:51am on April 30; the latest sunset is at 7:58pm on April 30; the latest sunrise is at 6:39am on April 1; the earliest sunset is at 7:25pm 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 67% (partly cloudy) to 75% (partly cloudy). The trend is for the sky to be clearing with the median cloud cover decreasing by 8% from the start to the end of the month.
On April 15, a representative day, the sky is clear or mostly clear 39% of the time, partly cloudy 11% of the time, and mostly cloudy or overcast 50% of the time.
The average probability that some form of precipitation will be observed in a given day is 51%, with little variation over the course of the month.
Throughout April, the most common forms of precipitation are light rain, moderate rain, thunderstorms, and light snow.
Light rain is the most severe precipitation observed during 33% of those days with precipitation. It is most likely around April 29, when it is observed during 19% of all days.
Moderate rain is the most severe precipitation observed during 20% of those days with precipitation. It is most likely around April 29, when it is observed during 12% of all days.
Thunderstorms are the most severe precipitation observed during 18% of those days with precipitation. They are most likely around April 30, when it is observed during 12% 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 15% of all days.
The likelihood of snow falling is highest around April 1, occurring in 21% 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 42% (comfortable) to 88% (very humid) over the course of a typical April, rarely dropping below 24% (dry) and reaching as high as 99% (very humid).
The air is driest around April 26, at which time the relative humidity drops below 50% (comfortable) three days out of four; it is most humid around April 1, rising above 82% (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 23Â°F (dry) to 45Â°F (dry) and is rarely below 11Â°F (dry) or above 58Â°F (comfortable).
Over the course of April typical wind speeds vary from 0 mph to 18 mph (calm to fresh breeze), rarely exceeding 25 mph (strong breeze).
The highest average wind speed of 11 mph (gentle breeze) occurs around April 7, at which time the average daily maximum wind speed is 18 mph (moderate breeze).
The lowest average wind speed of 10 mph (gentle breeze) occurs around April 30, at which time the average daily maximum wind speed is 16 mph (moderate breeze).