Winter Weather at Hartsfield-Jackson Atlanta International Airport Georgia, United StatesDaily high temperatures are around 57°F, rarely falling below 40°F or exceeding 73°F. The lowest daily average high temperature is 53°F on January 8. Daily low temperatures are around 39°F, rarely falling below 23°F or exceeding 55°F. The lowest daily average low temperature is 36°F on January 23. For reference, on July 21, the hottest day of the year, temperatures at Hartsfield-Jackson Atlanta International Airport typically range from 72°F to 89°F, while on January 23, the coldest day of the year, they range from 36°F to 53°F. The figure below shows you a compact characterization of the hourly average winter temperatures. The horizontal axis is the day, the vertical axis is the hour of the day, and the color is the average temperature for that hour and day. Sari, Iran (6,874 miles away); Yanjiang, China (8,000 miles); and Baiyun, China (8,047 miles) are the far-away foreign places with temperatures most similar to Hartsfield-Jackson Atlanta International Airport (view comparison). CloudsThe winter at Hartsfield-Jackson Atlanta International Airport experiences gradually increasing cloud cover, with the percentage of time that the sky is overcast or mostly cloudy increasing from 46% to 50%. The highest chance of overcast or mostly cloudy conditions is 54% on January 4. The clearest day of the winter is December 1, with clear, mostly clear, or partly cloudy conditions 54% of the time. For reference, on January 4, the cloudiest day of the year, the chance of overcast or mostly cloudy conditions is 54%, while on October 14, the clearest day of the year, the chance of clear, mostly clear, or partly cloudy skies is 67%. PrecipitationA wet day is one with at least 0.04 inches of liquid or liquid-equivalent precipitation. At Hartsfield-Jackson Atlanta International Airport, the chance of a wet day over the course of the winter is gradually increasing, starting the season at 27% and ending it at 29%. For reference, the year's highest daily chance of a wet day is 44% on July 8, and its lowest chance is 19% on October 28. Over the course of the winter at Hartsfield-Jackson Atlanta International Airport, the chance of a day with only rain remains an essentially constant 27% throughout, the chance of a day with mixed snow and rain remains an essentially constant 2% throughout, and the chance of a day with only snow remains an essentially constant 1% throughout. RainfallTo show variation within the season and not just the monthly totals, we show the rainfall accumulated over a sliding 31-day period centered around each day. The average sliding 31-day rainfall during the winter at Hartsfield-Jackson Atlanta International Airport is increasing, starting the season at 3.9 inches, when it rarely exceeds 6.7 inches or falls below 1.7 inches, and ending the season at 4.6 inches, when it rarely exceeds 7.3 inches or falls below 2.2 inches. The highest average 31-day accumulation is 4.6 inches on February 28. SnowfallAs with rainfall, we consider the snowfall accumulated over a sliding 31-day period centered around each day. The average sliding 31-day snowfall during the winter at Hartsfield-Jackson Atlanta International Airport is gradually increasing, starting the season at 0.2 inches, when it rarely exceeds 0.6 inches or falls below -0.0 inches, and ending the season at 0.5 inches, when it rarely exceeds 1.6 inches or falls below -0.0 inches. The highest average 31-day accumulation is 1.3 inches on January 17. SunOver the course of the winter at Hartsfield-Jackson Atlanta International Airport, the length of the day is rapidly increasing. From the start to the end of the season, the length of the day increases by 1 hour, 22 minutes, implying an average daily increase of 55 seconds, and weekly increase of 6 minutes, 28 seconds. The shortest day of the winter is December 21, with 9 hours, 55 minutes of daylight and the longest day is February 28, with 11 hours, 27 minutes of daylight. The latest sunrise of the winter at Hartsfield-Jackson Atlanta International Airport is 7:42 AM on January 7 and the earliest sunrise is 36 minutes earlier at 7:06 AM on February 28. The earliest sunset is 5:29 PM on December 4 and the latest sunset is 1 hour, 5 minutes later at 6:33 PM on February 28. Daylight saving time is observed at Hartsfield-Jackson Atlanta International Airport during 2024, but it neither starts nor ends during the winter, so the entire season is in standard time. For reference, on June 20, the longest day of the year, the Sun rises at 6:27 AM and sets 14 hours, 23 minutes later, at 8:51 PM, while on December 21, the shortest day of the year, it rises at 7:38 AM and sets 9 hours, 55 minutes later, at 5:33 PM. The figure below presents a compact representation of the sun's elevation (the angle of the sun above the horizon) and azimuth (its compass bearing) for every hour of every day in the reporting period. The horizontal axis is the day of the year and the vertical axis is the hour of the day. For a given day and hour of that day, the background color indicates the azimuth of the sun at that moment. The black isolines are contours of constant solar elevation. MoonThe figure below presents a compact representation of key lunar data for the winter of 2024. The horizontal axis is the day, the vertical axis is the hour of the day, and the colored areas indicate when the moon is above the horizon. The vertical gray bars (new Moons) and blue bars (full Moons) indicate key Moon phases. The label associated with each bar indicates the date and time that the phase is obtained, and the companion time labels indicate the rise and set times of the Moon for the nearest time interval in which the moon is above the horizon. HumidityWe base the humidity comfort level on the dew point, as it determines whether perspiration will evaporate from the skin, thereby cooling the body. Lower dew points feel drier and higher dew points feel more humid. Unlike temperature, which typically varies significantly between night and day, dew point tends to change more slowly, so while the temperature may drop at night, a muggy day is typically followed by a muggy night. The chance that a given day will be muggy at Hartsfield-Jackson Atlanta International Airport is essentially constant during the winter, remaining around 0% throughout. The lowest chance of a muggy day during the winter is 0% on January 17. For reference, on July 24, the muggiest day of the year, there are muggy conditions 85% of the time, while on January 15, the least muggy day of the year, there are muggy conditions 0% of the time. WindThis section discusses the wide-area hourly average wind vector (speed and direction) at 10 meters above the ground. The wind experienced at any given location is highly dependent on local topography and other factors, and instantaneous wind speed and direction vary more widely than hourly averages. The average hourly wind speed at Hartsfield-Jackson Atlanta International Airport is gradually increasing during the winter, increasing from 6.3 miles per hour to 7.1 miles per hour over the course of the season. For reference, on March 7, the windiest day of the year, the daily average wind speed is 7.1 miles per hour, while on August 4, the calmest day of the year, the daily average wind speed is 4.2 miles per hour. The wind direction at Hartsfield-Jackson Atlanta International Airport during the winter is predominantly out of the east from December 1 to December 2 and the west from December 2 to February 28. Growing SeasonDefinitions of the growing season vary throughout the world, but for the purposes of this report, we define it as the longest continuous period of non-freezing temperatures (≥ 32°F) in the year (the calendar year in the Northern Hemisphere, or from July 1 until June 30 in the Southern Hemisphere). The growing season at Hartsfield-Jackson Atlanta International Airport typically lasts for 8.2 months (252 days), from around March 14 to around November 20, rarely starting before February 14 or after April 7, and rarely ending before November 2 or after December 13. The winter at Hartsfield-Jackson Atlanta International Airport is more likely than not fully outside of the growing season, with the chance that a given day is in the growing season reaching a low of 0% on January 15. Growing degree days are a measure of yearly heat accumulation used to predict plant and animal development, and defined as the integral of warmth above a base temperature, discarding any excess above a maximum temperature. In this report, we use a base of 50°F and a cap of 86°F. The average accumulated growing degree days at Hartsfield-Jackson Atlanta International Airport are very rapidly decreasing during the winter, decreasing by 5,150°F, from 5,306°F to 156°F, over the course of the season. Solar EnergyThis section discusses the total daily incident shortwave solar energy reaching the surface of the ground over a wide area, taking full account of seasonal variations in the length of the day, the elevation of the Sun above the horizon, and absorption by clouds and other atmospheric constituents. Shortwave radiation includes visible light and ultraviolet radiation. The average daily incident shortwave solar energy at Hartsfield-Jackson Atlanta International Airport is increasing during the winter, rising by 1.4 kWh, from 2.8 kWh to 4.2 kWh, over the course of the season. The lowest average daily incident shortwave solar energy during the winter is 2.6 kWh on December 23. TopographyFor the purposes of this report, the geographical coordinates of Hartsfield-Jackson Atlanta International Airport are 33.641 deg latitude, -84.423 deg longitude, and 988 ft elevation. The topography within 2 miles of Hartsfield-Jackson Atlanta International Airport contains only modest variations in elevation, with a maximum elevation change of 190 feet and an average elevation above sea level of 975 feet. Within 10 miles also contains only modest variations in elevation (436 feet). Within 50 miles contains only modest variations in elevation (1,959 feet). The area within 2 miles of Hartsfield-Jackson Atlanta International Airport is covered by artificial surfaces (97%), within 10 miles by artificial surfaces (81%) and trees (17%), and within 50 miles by trees (58%) and artificial surfaces (26%). Data SourcesThis report illustrates the typical weather at Hartsfield-Jackson Atlanta International Airport, based on a statistical analysis of historical hourly weather reports and model reconstructions from January 1, 1980 to December 31, 2016. Temperature and Dew PointHartsfield-Jackson Atlanta International Airport has a weather station that reported reliably enough during the analysis period that we have included it in our network. When available, historical temperature and dew point measurements are taken directly from this weather station. These records are obtained from NOAA's Integrated Surface Hourly data set, falling back on ICAO METAR records as required. In the case of missing or erroneous measurements from this station, we fall back on records from nearby stations, adjusted according to typical seasonal and diurnal intra-station differences. For a given day of the year and hour of the day, the fallback station is selected to minimize the prediction error over the years for which there are measurements for both stations. The stations on which we may fall back include but are not limited to Fulton County Airport-Brown Field, Dekalb-Peachtree Airport, Dobbins Air Reserve Base, Atlanta Regional Airport, Newnan-Coweta County Airport, Cartersville Airport, Cherokee County Airport, and Cherokee County Airport. Other DataAll data relating to the Sun's position (e.g., sunrise and sunset) are computed using astronomical formulas from the book, Astronomical Algorithms 2nd Edition , by Jean Meeus. All other weather data, including cloud cover, precipitation, wind speed and direction, and solar flux, come from NASA's MERRA-2 Modern-Era Retrospective Analysis . This reanalysis combines a variety of wide-area measurements in a state-of-the-art global meteorological model to reconstruct the hourly history of weather throughout the world on a 50-kilometer grid. Land Use data comes from the Global Land Cover SHARE database , published by the Food and Agriculture Organization of the United Nations. Elevation data comes from the Shuttle Radar Topography Mission (SRTM) , published by NASA's Jet Propulsion Laboratory. Names, locations, and time zones of places and some airports come from the GeoNames Geographical Database . Time zones for airports and weather stations are provided by AskGeo.com . Maps are © OpenStreetMap contributors. DisclaimerThe information on this site is provided as is, without any assurances as to its accuracy or suitability for any purpose. Weather data is prone to errors, outages, and other defects. We assume no responsibility for any decisions made on the basis of the content presented on this site. We draw particular cautious attention to our reliance on the MERRA-2 model-based reconstructions for a number of important data series. While having the tremendous advantages of temporal and spatial completeness, these reconstructions: (1) are based on computer models that may have model-based errors, (2) are coarsely sampled on a 50 km grid and are therefore unable to reconstruct the local variations of many microclimates, and (3) have particular difficulty with the weather in some coastal areas, especially small islands. 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