This report describes the typical weather at the Evansville Regional Airport (Evansville, Indiana, United States) weather station over the course of an average December. It is based on the historical records from 1974 to 2012. Earlier records are either unavailable or unreliable.
Evansville, Indiana has a warm humid temperate climate with hot summers and no dry season. The area within 25 mi of this station is covered by croplands (85%), forests (8%), grasslands (3%), lakes and rivers (3%), and built-up areas (2%).
The month of December is characterized by falling daily high temperatures, with daily highs decreasing from 49°F to 41°F over the course of the month, exceeding 63°F or dropping below 25°F only one day in ten.
Over the course of December, the length of the day is essentially constant. The shortest day of the month is December 20 with 9:31 hours of daylight; the longest day is December 1 with 9:42 hours of daylight.
The earliest sunrise is at 6:48am on December 1; the latest sunset is at 4:40pm on December 31; the latest sunrise is at 7:07am on December 31; the earliest sunset is at 4:30pm on December 6.
Daylight savings time is observed in 2012 but it neither starts nor ends in December, so the entire month is in standard time.
The median cloud cover ranges from 76% (partly cloudy) to 90% (mostly cloudy). The trend is for the sky to be becoming cloudier with the median cloud cover increasing by 14% from the start to the end of the month.
On December 1, the clearest day of the month, the sky is clear, mostly clear, or partly cloudy 48% of the time, and overcast or mostly cloudy 52% of the time.
On December 25, the cloudiest day of the month, the sky is overcast, mostly cloudy, or partly cloudy 64% of the time, and clear or mostly clear 36% of the time.
The probability that precipitation will be observed at this location varies throughout the month. Precipitation is most likely around December 25, occurring in 54% of days. Precipitation is least likely around December 1, occurring in 49% of days.
Throughout December, the most common forms of precipitation are light snow, moderate rain, and light rain.
Light snow is the most severe precipitation observed during 27% of those days with precipitation. It is most likely around December 31, when it is observed during 18% of all days.
Moderate rain is the most severe precipitation observed during 27% of those days with precipitation. It is most likely around December 1, when it is observed during 15% of all days.
Light rain is the most severe precipitation observed during 22% of those days with precipitation. It is most likely around December 1, when it is observed during 13% of all days.
The likelihood of snow falling is highest around December 31, occurring in 25% of days.
Accumulation at this location in December is unlikely. The chances of there being snow on the ground are highest around December 31, occurring 14% of the time.
The snow is typically at its deepest on December 15, with a median depth of 1.4"; the depth exceeds 2.2" only one year out of ten.
The relative humidity typically ranges from 57% (mildly humid) to 89% (very humid) over the course of a typical December, rarely dropping below 38% (comfortable) and reaching as high as 99% (very humid).
The air is driest around December 1, at which time the relative humidity drops below 67% (mildly humid) three days out of four; it is most humid around December 21, rising above 85% (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 December, the dew point typically varies from 20°F (dry) to 38°F (dry) and is rarely below 3°F (dry) or above 55°F (very comfortable).
Over the course of December typical wind speeds vary from 0 mph to 14 mph (calm to moderate breeze), rarely exceeding 21 mph (fresh breeze).
The highest average wind speed of 8 mph (gentle breeze) occurs around December 5, at which time the average daily maximum wind speed is 14 mph (moderate breeze).
The lowest average wind speed of 8 mph (gentle breeze) occurs around December 17, at which time the average daily maximum wind speed is 14 mph (moderate breeze).