This report describes the typical weather at the Birmingham International Airport (Birmingham, Alabama, United States) 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.
Birmingham, Alabama has a warm humid temperate climate with hot summers and no dry season. The area within 25 mi of this station is covered by forests (82%), built-up areas (9%), and croplands (8%).
The month of May is characterized by rising daily high temperatures, with daily highs increasing from 77°F to 84°F over the course of the month, exceeding 91°F or dropping below 68°F only one day in ten.
Over the course of May, the length of the day is gradually increasing. The shortest day of the month is May 1 with 13:33 hours of daylight; the longest day is May 31 with 14:14 hours of daylight.
The earliest sunrise is at 5:38am on May 31; the latest sunset is at 7:52pm on May 31; the latest sunrise is at 5:58am on May 1; the earliest sunset is at 7:30pm 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 is 54% (partly cloudy) and does not vary substantially over the course of the month.
On May 16, a representative day, the sky is clear or mostly clear 40% of the time, partly cloudy 19% of the time, and mostly cloudy or overcast 41% of the time.
The average probability that some form of precipitation will be observed in a given day is 41%, with little variation over the course of the month.
Throughout May, the most common forms of precipitation are thunderstorms, light rain, and moderate rain.
Thunderstorms are the most severe precipitation observed during 57% of those days with precipitation. They are most likely around May 31, when it is observed during 27% of all days.
Light rain is the most severe precipitation observed during 24% of those days with precipitation. It is most likely around May 3, when it is observed during 11% of all days.
Moderate rain is the most severe precipitation observed during 14% of those days with precipitation. It is most likely around May 1, when it is observed during 6% of all days.
Either snow is exceptionally unlikely to fall at this location in May or this station does not reliably report precipitation types.
The relative humidity typically ranges from 44% (comfortable) to 93% (very humid) over the course of a typical May, rarely dropping below 27% (dry) and reaching as high as 100% (very humid).
The air is driest around May 1, at which time the relative humidity drops below 53% (mildly humid) three days out of four; it is most humid around May 6, rising above 89% (very 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 49°F (dry) to 67°F (muggy) and is rarely below 37°F (dry) or above 73°F (very muggy).
The time of the month between May 1 and May 24 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 0 mph to 14 mph (calm to moderate breeze), rarely exceeding 18 mph (fresh breeze).
The highest average wind speed of 7 mph (light breeze) occurs around May 1, at which time the average daily maximum wind speed is 14 mph (moderate breeze).
The lowest average wind speed of 6 mph (light breeze) occurs around May 31, at which time the average daily maximum wind speed is 12 mph (gentle breeze).