Summer temperatures for the United States as a whole are getting warmer based on instrumental records kept by NOAA as well as other groups.  In some places in the north, that is not all bad.  However, in places that are already warm, hotter temperatures could cause economic losses from increased use of air conditioning, reduced production and health of cattle due to heat stress, and need for extra cooling of outdoor workers.

So how much have summer temperatures changed across the Southeast?  I used the Climate at a Glance tool from NOAA to take a look.  The first graph below shows the trend for the continental US for summer, with an upward trend over time, although of course there are some ups and downs.  The second figure shows the same thing except just for Georgia.  Note that for Georgia over the time period 1895-2015, the trend is slightly downward, indicating cooler temperatures.  But a lot of that is tied to warm temperatures in the first half of the record.  The third graph shows the same data but now the trend line is just for 1960-2015.  Note that there is a fairly steep rise in temperatures (keeping in mind that not all graphs have the same scale) from 1960 to the present.  This is part of the reason that the Climate Prediction Center predicts that we have a greater chance of above normal temperatures this summer–they take into account the trend over the last 50 years more than the last 100 plus years, since modern data are more reliable and more representative of current urbanization and land use patterns.

The short answer is that the summers in the Southeast are getting warmer if you look at just the time period from 1960-present, but less so if you look at the longer time period.  And of course year-to-year variability will continue to affect crop farmers more than the small increase we see over time from a warmer planet, especially on the planning time scales of 1-2 years that most farmers use to make farm management decisions.  But down the road the warmer conditions might allow farmers to do more double- or even triple-cropping as the growing season length increases (my research shows about 1 week per 1 degree F) and also make them think about the most productive crops to grow in a warmer climate.

PS If you compare daytime max temperatures to nighttime minimum temperatures, you will see that all the warming trend since 1960 comes from increases in nighttime temperatures and none from daytime.  This could have implications for the health of people and animals that need a cooling-off period at night.  Variability from one year to the next in maximum temperatures has increased, though, which makes planning more difficult.

us summer temp trendUS June-August temperature with long-term trend line

ga summer temp trendGeorgia June-August temperature with long-term trend line

ga sum temp with short trend Georgia June-August temperature trend from 1960-2015