June’s combination of heat and humidity made coastal Georgia feel more like a tropical jungle at times.
But the stifling spell of days with heat indexes at or near 110 degrees also offered a glimpse into the likely impact of heat-trapping pollution on local weather patterns, according to analyses from Climate Central.
Based on historical data, conditions Monday and Tuesday – when heat-index readings in Savannah hit 108 and 110, respectively – were three times more likely to be caused by climate change, the organization found.
Put another way, the odds of hitting the elevated maximum and minimum temperatures experienced on those days were three times higher than they were before climate change began significantly affecting weather patterns.
For Wednesday and Thursday, the Climate Central’s Climate Shift Index determined the conditions were two times more likely to be the result of carbon emissions.
“Human-caused climate change is having a measurable impact on local weather conditions … in Savannah,” said Lauren Casey, a Climate Central meteorologist.
A key factor in that determination is a more frequent pairing of extremely warm days and nights.
The historical normal low in Savannah for this period in June is about 72 degrees, according to the National Weather Service. The average low temperature Monday through Thursday of last week was more than 77 degrees.
Climate Central also found that Savannah is eight times more likely to experience the combination of an extremely warm day and night than it was a half-century ago.
That category involves days when both highs and lows are warmer than 90% of previous days of the same date over time.
That now happens eight times per year in Savannah, on average, compared to just once annually in the 1970s. That’s the most among the half-dozen Georgia cities included in the analysis. The area hit that threshold twice last week and at least three times so far since the summer season began.
The average high temperature Monday through Wednesday of last week was 95 degrees, according to NWS. That’s about 4 degrees above normal.
Swelter weather:Extreme heat, warm nights making Savannah summers steamier
Cities in the Southeast have had the most-significant temperature anomalies this week, Climate Central found.
“Climate change has made the extreme heat that is pummeling the U.S. this summer much more likely and much more intense,” said Andrew Pershing, the organization’s vice president for science. “This is an unnatural disaster that is directly linked to carbon pollution from coal, oil and natural gas.”
As previously reported by the Savannah Morning News, the area’s annual average of warmer-than-normal summer days – based on historical data – has climbed by the equivalent of more than three weeks over the past half-century.
In 2023, it happened 58 times.
Savannah is on a similar pace this year. From June 5 through June 27, average temperatures (factoring in highs and lows) were above normal for 19 of 23 days, according to NWS.
The all-time summer peak was 82 warmer-than-usual days in 2016.
The lowest totals were 11 in 1974 and 15 two years later.
Extreme heat poses a particular threat to children, adults older than 65, pregnant women and people living with illness.
Warmer summer weather also drives up energy use, including at night when temperatures remain relatively high and air conditioners run longer.
John Deem covers climate change and the environment in coastal Georgia. He can be reached at 912-652-0213 or jdeem@gannett.com.