This report describes the typical weather at the Vienna International Airport (Schwechat Airport) (Vienna, Austria) weather station over the course of an average May. It is based on the historical records from 1974 to 2012. Earlier records are either unavailable or unreliable.
Vienna has a humid continental climate with warm summers and no dry season. The area within 25 mi of this station is covered by croplands (78%), grasslands (11%), forests (5%), built-up areas (5%), and lakes and rivers (3%).
The month of May is characterized by rising daily high temperatures, with daily highs increasing from 65°F to 71°F over the course of the month, exceeding 81°F or dropping below 54°F only one day in ten.
Over the course of May, 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 May 1 with 14:33 hours of daylight; the longest day is May 31 with 15:47 hours of daylight.
The earliest sunrise is at 4:59am on May 30; the latest sunset is at 8:45pm on May 31; the latest sunrise is at 5:35am on May 1; the earliest sunset is at 8:08pm on May 1.
Daylight savings time is observed in 2012 but it neither starts nor ends in May, so the entire month is in daylight time.
The median cloud cover ranges from 54% (partly cloudy) to 59% (partly cloudy). The trend is for the sky to be clearing with the median cloud cover decreasing by 5% from the start to the end of the month.
On May 16, a representative day, the sky is clear or mostly clear 38% of the time, partly cloudy 25% of the time, and mostly cloudy or overcast 31% of the time.
The average probability that some form of precipitation will be observed in a given day is 53%, with little variation over the course of the month.
Throughout May, the most common forms of precipitation are moderate rain, thunderstorms, and light rain.
Moderate rain is the most severe precipitation observed during 59% of those days with precipitation. It is most likely around May 5, when it is observed during 33% of all days.
Thunderstorms are the most severe precipitation observed during 24% of those days with precipitation. They are most likely around May 31, when it is observed during 16% of all days.
Light rain is the most severe precipitation observed during 14% of those days with precipitation. It is most likely around May 18, when it is observed during 8% of all days.
The likelihood of snow falling is highest around May 1, occurring in 2% of days.
Either snow rarely accumulates at this location in May or snow depth measurements are unavailable or unreliable.
The relative humidity typically ranges from 45% (comfortable) to 89% (very humid) over the course of a typical May, rarely dropping below 32% (comfortable) and reaching as high as 99% (very humid).
The air is driest around May 1, at which time the relative humidity drops below 51% (mildly humid) three days out of four; it is most humid around May 25, 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 May, the dew point typically varies from 39°F (dry) to 55°F (very comfortable) and is rarely below 29°F (dry) or above 62°F (mildy humid).
The time of the month between May 9 and May 31 is the most comfortable, with dew points that are neither too dry nor too muggy.
Over the course of May typical wind speeds vary from 2 mph to 16 mph (light air to moderate breeze), rarely exceeding 24 mph (strong breeze).
The highest average wind speed of 9 mph (gentle breeze) occurs around May 1, at which time the average daily maximum wind speed is 16 mph (moderate breeze).
The lowest average wind speed of 9 mph (gentle breeze) occurs around May 20, at which time the average daily maximum wind speed is 15 mph (moderate breeze).