This report describes the typical weather at the Dane County Regional Airport (Madison, Wisconsin, 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.
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 January is characterized by essentially constant daily high temperatures, with daily highs around 27Â°F throughout the month, exceeding 41Â°F or dropping below 10Â°F only one day in ten.
Over the course of January, the length of the day is gradually increasing. From the start to the end of the month, the length of the day increases by 51 minutes, implying an average day-over-day increase of 1.6 minutes.
The shortest day of the month is January 1 with 9:03 hours of daylight; the longest day is January 31 with 9:54 hours of daylight.
The earliest sunrise is at 7:14am on January 31; the latest sunset is at 5:08pm on January 31; the latest sunrise is at 7:30am on January 2; the earliest sunset is at 4:32pm on January 1.
Daylight savings time is observed in 2012 but it neither starts nor ends in January, so the entire month is in standard time.
The median cloud cover is 87% (mostly cloudy) and does not vary substantially over the course of the month.
On January 16, a representative day, the sky is clear or mostly clear 36% of the time, partly cloudy 8% of the time, and mostly cloudy or overcast 56% of the time.
The average probability that some form of precipitation will be observed in a given day is 60%, with little variation over the course of the month.
Throughout January, the most common forms of precipitation are light snow and moderate snow.
Light snow is the most severe precipitation observed during 65% of those days with precipitation. It is most likely around January 15, when it is observed during 41% of all days.
Moderate snow is the most severe precipitation observed during 17% of those days with precipitation. It is most likely around January 29, when it is observed during 11% of all days.
The likelihood of snow falling is highest around January 15, occurring in 53% of days.
Accumulation at this location in January is likely. The chances of there being snow on the ground are highest around January 31, occurring 82% of the time.
The snow is typically at its deepest on January 30, with a median depth of 5.0"; the depth exceeds 11.7" only one year out of ten.
The relative humidity typically ranges from 59% (mildly humid) to 88% (very humid) over the course of a typical January, rarely dropping below 42% (comfortable) and reaching as high as 98% (very humid).
The air is driest around January 31, at which time the relative humidity drops below 69% (mildly humid) three days out of four; it is most humid around January 1, rising above 83% (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 4Â°F (dry) to 21Â°F (dry) and is rarely below -16Â°F (dry) or above 34Â°F (dry).
Over the course of January typical wind speeds vary from 1 mph to 15 mph (light air to moderate breeze), rarely exceeding 22 mph (fresh breeze).
The highest average wind speed of 9 mph (gentle breeze) occurs around January 18, at which time the average daily maximum wind speed is 15 mph (moderate breeze).
The lowest average wind speed of 9 mph (gentle breeze) occurs around January 5, at which time the average daily maximum wind speed is 15 mph (moderate breeze).