Weather + Climate

Monthly weather and climate data can be found here for the State of Georgia and the City of Atlanta. All Atlanta data is from National Weather Service instruments located at Hartsfield-Jackson Atlanta International Airport. Data has been collected at that site since 1930. 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).

Keep in mind that scientists don’t simply look at raw data to assess changes in the climate. Quality control methods must be applied to weather stations to ensure they are not capturing inaccurate or erroneous data. Adjustments of observed temperatures may also occur. As land gets developed, localized temperatures generally warm. This is known as the urban heat island effect. Scientists must adjust for this as well as changes in the quality of instrumentation over time. The significant bulk of adjustments have occurred to data observed prior to 1940 and those adjustments have generally resulted in warmer temperatures. The adjustments made over the past several decades have generally resulted in minimal changes from the observed data. Popular Mechanics has a good article about how scientists determined in 2012 that the old global temperature record of 136.4°F recorded in Libya in 1922 was not credible. Death Valley, California now holds the global record of 134°F, recorded in 1913.

 

Current Conditions

Current Temperature Chart (Blue Line-Red Digits)

This is the top 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.

Historical Monthly Temperature Chart (Colored Dots)

The chart with the colored dots on the right (desktop) or below (mobile) shows the average month-to-date temperature for all years going back to 1930. The black star represents 2018. The month-to-date average temperature is the average temperature from the first of the month through today. For example, on June 30 there were 8 years with warmer June 1 to June 30 (month-to-date) average temperatures than June 1 to June 30, 2018. That makes June 1 to June 30, 2018 the 9th warmest June 1 to June 30 on record, which is reflected on the bottom chart.

Monthly Rank Chart

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.


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 (red 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.

GA Average Temperature Chart, January 2018 to July 2018

 

July Analysis

A cooler, but slightly above average July 2018 pushed the year-to-date ranking back one spot to 29th.


City of Atlanta Average Temperature

The figure below shows the actual average monthly temperatures at Hartsfield Jackson Atlanta International Airport versus the normal average monthly temperatures. The numbers at the base of 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.

ATL Temperature Chart, January 2017 to July 2018


July Analysis

July temperatures were only 0.6°F above average. July is the hottest month in Atlanta, so record highs tend to be in the upper 90’s and low to mid 100’s. We got nowhere close to any records. Only 5 of the previous 19 months have had below average temperatures.


 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.

July Analysis

Thanks to 3 inches of rain on July 14, the month ended with Atlanta receiving over 8 inches of rain. That pushes our yearly surplus to 7.29 inches.


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.

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.

 

June Analysis

We’ve seen about average rainfall so far this year and June was no different. Drought conditions that had crept into eastern Georgia earlier in the year have subsided and all districts remain drought-free.

 


 

Related Articles