Weather + Climate
Last Update: 07 June 2018
Monthly weather and climate data can be found here for the State of Georgia and the City of Atlanta. Quick data points and rankings are posted on the right side of the homepage (below posts for mobile users). All data is pulled from the National Oceanic and Atmospheric Administration (NOAA) websites and is updated on a daily and monthly basis. Georgia temperature data and drought data for the previous month is released by NOAA several days into the new month (ex: January data is released around Feb 7th).
Below is the same chart that appears to the right (desktop) or below the article (mobile). All data is updated on an hourly basis. The two right-most data points show today’s average temperature and the normal average temperature for today. The average temperature is simply the high for the day plus the low for the day, divided by two. NOAA’s definition of “normal” is based on data collected between 1980 and 2010. The third chart on the right (desktop) or below (mobile) shows how temperatures up to this point in the month compare to historical temperatures up to this point in the month going back to 1930. Since our graphs update on an hourly basis, the ranking may change throughout the day as today’s latest temperatures get incorporated into the historical comparison.
The chart with the blue temperature values on the right (desktop) or below (mobile) shows the minimum average temperature needed today for the current month to be the 1st warmest on record. It also shows the maximum average temperature needed today for the current month to be the 1st coldest on record. This provides some perspective into how warm or cool temperatures have been up to this point in the month. For instance, in order to undo the warmth we’ve seen between May 1 and May 20, the average temperature on May 21 would have to be -193°F to make May 1- May 21 the coldest such period on record, but would only have to be 69°F to make it the warmest such period on record.
State of Georgia Average Temperature
The figure below shows the average temperature up to that point in the year for the State of Georgia versus the historical 20th Century Average for that time period. Average daily temperatures are calculated by adding the high temperature to the low temperature and dividing by two. All the daily average temperatures are then used to determine the monthly average temperature.
NOAA has provided a ranking tool to put the data into historical context. Using 123 years of recorded data, the tool shows you how data for a particular time period compares to historical data for that time period.
The chart below uses the Year-to-Date feature to show how warm or cool the year has been up to that point compared to previous years up to that point. For example, the average temperature in Georgia from January 1, 2017 to February 28, 2017 was 54.8ºF (orange bar). Historically, the average temperature during that period is 47.4 °F (black line). This is a departure from the historical average of +7.4 °F. In 123 years of record keeping, January 1, 2017 to February 28, 2017 was the 3rd warmest such time period of any year.
May temperatures throughout Georgia were 2.4°F above average making May 2018 the 17th warmest May on record for Georgia. This pushed the year-to-date average temperature ranking from 79th to 33rd. Since January 2017, Georgia’s year-to-date average temperature has been below the historical average temperature only once: during the month of January 2018 (Jan 1 – Jan 31, 2018).
City of Atlanta Average Temperature
The figure below shows the actual average monthly temperatures at Atlanta Hartsfield International Airport versus the normal average monthly temperatures. The numbers above each bar represent the difference between the actual average monthly temperature the normal average monthly temperature. For example, in April 2017 the actual average monthly temperature was 67.8 °F and the normal average monthly temperature was 62.0°F. The average temperature was therefore 5.8°F above normal. The Year-to-Date is the average of the actual and normal monthly temperatures from January 1st to the end of the previous month. All data is from the National Weather Service Forecast Office in Peachtree City, GA.
May temperatures were 4.7°F above average, making May 2018 the warmest May on record. While temperatures in January, March, and April were below average, the year-to-date average temperature is 2.1°F above average due to very warm temperatures in February and May. As the chart below shows, the only day in May where the daily low was below the normal daily low was May 1. Record high temperatures were recorded on May 12, 13, and 14th.
Atlanta Average Precipitation
The chart below shows the actual monthly precipitation recorded at Atlanta Hartsfield International Airport (blue bar) versus the average monthly precipitation (blue line). All data is from the National Weather Service Forecast Office in Peachtree City, GA.
May precipitation was 1.18 inches above average, which pushed the 2018 precipitation surplus close to 4 inches.
The Palmer Drought Severity Index (PDSI) is a widely used model designed to predict drought conditions. The PDSI has its advantages and disadvantages, but NOAA and state and local governments use it to assess drought conditions over time. Negative numbers correspond to drier conditions while positive numbers correspond to wetter conditions. A PDSI value of -4.0 or below corresponds to extreme drought conditions.
Each state is divided into climate divisions with Georgia having nine division. They are numbered from northwest to southeast; metro Atlanta is in District 2 (second from top left) as is Lake Lanier, one of the state’s most important reservoirs. Drought conditions both upstream and downstream of Lake Lanier will influence the reservoir’s water levels. Drier conditions in District 2 and 3 will result in less water flowing into Lake Lanier while wetter conditions in south Georgia and Florida can result in less water being released from Lake Lanier. Tensions in the water wars between Georgia, Florida, and Alabama escalate as drier conditions increase in the southeast region. Below is a GIF of PDSI values for every climate division the country.
Thanks to a wetter-than-normal April, drought conditions in District 3 (NE corner of GA) have subsided. Moderate drought conditions remain in Districts 6 and 9. Out in the west, the recurring summer drought conditions are re-appearing in California, Arizona, and New Mexico.