This report describes the typical weather at the Hartsfield-Jackson Atlanta International Airport (Atlanta, Georgia, United States) weather station over the course of an average year. It is based on the historical records from 1974 to 2012. Earlier records are either unavailable or unreliable.
Atlanta, Georgia 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 (47%), forests (29%), and built-up areas (23%).
Over the course of a year, the temperature typically varies from 34°F to 89°F and is rarely below 20°F or above 95°F.
The warm season lasts from May 23 to September 19 with an average daily high temperature above 81°F. The hottest day of the year is July 18, with an average high of 89°F and low of 72°F.
The cold season lasts from November 30 to February 21 with an average daily high temperature below 59°F. The coldest day of the year is January 18, with an average low of 34°F and high of 51°F.
The length of the day varies significantly over the course of the year. The shortest day is December 21 with 9:55 hours of daylight; the longest day is June 20 with 14:24 hours of daylight.
The earliest sunrise is at 6:26am on June 8 and the latest sunset is at 8:53pm on June 26. The latest sunrise is at 7:59am on November 3 and the earliest sunset is at 5:29pm on December 3.
Daylight savings time (DST) is observed in this location during 2012, starting in the spring on March 11 and ending in the fall on November 4.
The median cloud cover ranges from 45% (partly cloudy) to 82% (mostly cloudy). The sky is cloudiest on January 8 and clearest on October 8. The clearer part of the year begins around April 2. The cloudier part of the year begins around November 27.
On October 8, the clearest day of the year, the sky is clear, mostly clear, or partly cloudy 62% of the time, and overcast or mostly cloudy 37% of the time.
On January 8, the cloudiest day of the year, the sky is overcast, mostly cloudy, or partly cloudy 65% of the time, and clear or mostly clear 34% of the time.
The probability that precipitation will be observed at this location varies throughout the year. Precipitation is most likely around July 22, occurring in 50% of days. Precipitation is least likely around October 14, occurring in 32% of days.
Over the entire year, the most common forms of precipitation are thunderstorms, moderate rain, and light rain.
Thunderstorms are the most severe precipitation observed during 31% of those days with precipitation. They are most likely around July 12, when it is observed during 31% of all days.
Moderate rain is the most severe precipitation observed during 28% of those days with precipitation. It is most likely around December 20, when it is observed during 16% of all days.
Light rain is the most severe precipitation observed during 27% of those days with precipitation. It is most likely around January 11, when it is observed during 15% of all days.
During the warm season, which lasts from May 23 to September 19, there is a 46% average chance that precipitation will be observed at some point during a given day. When precipitation does occur it is most often in the form of thunderstorms (53% of days with precipitation have at worst thunderstorms), moderate rain (21%), and light rain (19%).
During the cold season, which lasts from November 30 to February 21, there is a 45% average chance that precipitation will be observed at some point during a given day. When precipitation does occur it is most often in the form of moderate rain (34% of days with precipitation have at worst moderate rain), light rain (31%), heavy rain (8%), and thunderstorms (8%).
The likelihood of snow falling is highest around February 2, occurring in 7% of days.
Either snow rarely accumulates at this location or snow depth measurements are unavailable or unreliable.
The relative humidity typically ranges from 39% (comfortable) to 91% (very humid) over the course of the year, rarely dropping below 21% (dry) and reaching as high as 100% (very humid).
The air is driest around April 11, at which time the relative humidity drops below 48% (comfortable) three days out of four; it is most humid around August 2, exceeding 88% (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 year, the dew point typically varies from 23°F (dry) to 72°F (very muggy) and is rarely below 6°F (dry) or above 75°F (very muggy).
There are two periods in the year that are most comfortable: The first is between April 4 and June 2 and the second is between September 17 and November 5. The air feels neither too dry nor too muggy during these periods.
Over the course of the year typical wind speeds vary from 0 mph to 17 mph (calm to moderate breeze), rarely exceeding 25 mph (strong breeze).
The highest average wind speed of 10 mph (gentle breeze) occurs around March 3, at which time the average daily maximum wind speed is 17 mph (moderate breeze).
The lowest average wind speed of 7 mph (light breeze) occurs around August 18, at which time the average daily maximum wind speed is 12 mph (moderate breeze).