Weather + Climate

Last Update: 08 Sept 2017

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 left side of the homepage. All data is pulled from the National Oceanic and Atmospheric Administration (NOAA) websites and is updated monthly. We’ll be adding much more data and information in the future.

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 greater 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 54.8 ºF (blue bar). Historically, the average temperature during that period is 47.4 °F (blue 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. The average temperature in Georgia between January 1, 2017 and June 30, 2017 was 67.3 °F while the historical average temperature for that time period is 63.8 °F. In 123 years of record keeping, January 1, 2017 to June 30, 2017 was the warmest such time period of any year.

GA AVG TEMP JANAUG

 

City of Atlanta Average Temperature

The figure below shows the actual average monthly temperatures at Atlanta Hartsfield International Airport for 2017 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 the actual average monthly temperature was 67.8 °F and the normal average monthly temperature was 62.0 °F. 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.

ATL AVG TEMP JANAUG

Note: this chart was updated on 09 Sept 2017 to reflect a change in the August average temperature. The updated data shows that the average temperature was .2°F below the normal average August temperature.

 

Atlanta Average Precipitation

The chart below shows the actual monthly precipitation recorded at Atlanta Hartsfield International Airport (blue and white bar) versus the average monthly precipitation (blue line). The numbers above the bars represent the difference between the actual rainfall and the average rainfall for that time period. For example, rainfall in January 2017 was 8.18 inches while the average rainfall is 4.20 inches. The difference is +3.98 inches. All data is from the National Weather Service Forecast Office in Peachtree City, GA.

 

ATL AVG MONTHLY PRECIP JANAUG

Drought Conditions

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.

NOAA has divided Georgia into nine climate divisions and PDSI values are given for each district. Most of metro Atlanta is in District 2 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. Dryer conditions in District 2 and 3 will result in less water flowing into Lake Lanier while wetter conditions in South Georgia can result in less water being released from Lake Lanier.

August Analysis

Chart 1, below, shows the PDSI values from Jan 1, 2017 – July 31, 2017 for each district. Districts 1 and 2 experienced moderate drought conditions while District 3 experienced extreme drought conditions during this time period.

YTD 2017 PDSI

Chart 1: PDSI Values for Jan 1, 2017 – July 31, 2017

Chart 2 shows the PDSI values for each district during the same time period in 2016. There is no error with that chart: each district experienced mid-range or normal conditions between Jan 1, 2016 and July 31, 2016.

PDSI 2016 Jan July

Chart 2: PDSI Values for Jan 1, 2016 – July 31, 2016

Finally, chart 3 shows the percent change between 2016 PDSI values and 2017 PDSI values. Each district experienced drier conditions between Jan 1, 2017 and July 31, 2017 than they did during that same time period in 2016. District 8 saw the greatest percent change in PDSI values, though District 3 went from mid-range/normal in 2016 to extreme drought conditions in 2017.

2016 2017 PDSI Diff

Chart 3: Percent Change in PDSI Values from Jan 1, 2016 – July 31, 2016 to Jan 1, 2017 – July 31, 2017