This report describes the typical weather at the Chattanooga Metropolitan Airport (Chattanooga, Tennessee, 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.
Chattanooga, Tennessee 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 (89%), built-up areas (6%), lakes and rivers (3%), and croplands (3%).
The month of May is characterized by rising daily high temperatures, with daily highs increasing from 76°F to 83°F over the course of the month, exceeding 90°F or dropping below 66°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 13:38 hours of daylight; the longest day is May 30 with 14:21 hours of daylight.
The earliest sunrise is at 6:28am on May 30; the latest sunset is at 8:49pm on May 31; the latest sunrise is at 6:49am on May 1; the earliest sunset is at 8:27pm 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 43% of the time, partly cloudy 17% of the time, and mostly cloudy or overcast 39% of the time.
The average probability that some form of precipitation will be observed in a given day is 44%, with little variation over the course of the month.
Throughout May, the most common forms of precipitation are thunderstorms, moderate rain, and light rain.
Thunderstorms are the most severe precipitation observed during 50% of those days with precipitation. They are most likely around May 31, when it is observed during 26% of all days.
Moderate rain is the most severe precipitation observed during 24% of those days with precipitation. It is most likely around May 8, when it is observed during 11% of all days.
Light rain is the most severe precipitation observed during 21% of those days with precipitation. It is most likely around May 1, when it is observed during 11% 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 43% (comfortable) to 94% (very humid) over the course of a typical May, rarely dropping below 26% (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 31, rising above 91% (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 47°F (dry) to 66°F (muggy) and is rarely below 34°F (dry) or above 72°F (very muggy).
The time of the month between May 1 and May 29 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 13 mph (calm to moderate breeze), rarely exceeding 18 mph (fresh breeze).
The highest average wind speed of 6 mph (light breeze) occurs around May 1, at which time the average daily maximum wind speed is 13 mph (moderate breeze).
The lowest average wind speed of 5 mph (light breeze) occurs around May 31, at which time the average daily maximum wind speed is 12 mph (gentle breeze).