After three consecutive summers that ranked among the hottest on record, the summer of 2013 brought welcome relief in the form of cooler than normal temperatures and abundant rainfall to Kentucky.
After a typical June, both July and August were well below normal with afternoon temperatures that rarely reached 90 degrees. Bowling Green went 38 consecutive days from July 21 to Aug. 27 without having a high temperature of at least 90, which was the second longest summertime sub-90 degrees streak dating to 1894.
It was also a summer where the high temperature never surpassed 95 degrees, which typically occurs 14 times per summer. Overall, the summer of 2013 was the 33rd coolest summer in the last 120 years, although the July-August period ranked as the 18th coolest.
The culprit for the cool summer was an active storm track that brought numerous rain chances to south central Kentucky all summer long. According to Dr. Greg Goodrich, Associate Professor of Meteorology in WKU’s Department of Geography and Geology, the persistent clouds and storms often put a cap on afternoon temperatures.
“The cloudiness and high humidity from the numerous storms this summer kept afternoon temperatures well below normal but also kept our mornings warm and muggy,” Dr. Goodrich said. “We also never had any long stretches without rainfall, which kept our soils from drying out and adding heat to the atmosphere. The longest stretch without measurable rainfall was only seven days, whereas the typical summer will have dry stretches that can last a couple of weeks.”
Overall, the summer of 2013 was the seventh wettest on record with more than 18 inches and the wettest since 2009. The two-month period from July to August was the second wettest such period with nearly 16 inches, second only to 1938. It could have been worse. June was drier than normal with only 2.4 inches of rain in Bowling Green, but the Bluegrass region had nearly 7 inches in June as did several counties to the west of Bowling Green.
“Summertime thunderstorms are often hit-or-miss, and while a number of soaking thunderstorms just missed us in June, nearly every thunderstorm in July and August came right through this area,” Dr. Goodrich said.
More than 42 inches of rain have fallen in Bowling Green so far through the first eight months of the year, which ranks as the ninth wettest start to the year and the wettest January-August period since 1994. The summer of 2013 ranks as the fifth straight extreme summer in a row, as both 2009 and 2013 were similarly cool and wet while 2010, 2011 and 2012 were uncomfortably hot. The summer of 2008 was the most recent “normal” summer and even it was preceded by the extremely hot and dry summer of 2007.
“Recent summers have highlighted the variability of our climate,” said state climatologist Stuart Foster, director of the Kentucky Climate Center and the Kentucky Mesonet at WKU. “After experiencing a period of drought and extreme heat last summer, Kentucky has experienced fewer outbreaks of severe weather this summer. While residents have saved on their energy bills this summer, they have spent more time keeping their lawns mowed.”
While warmer weather has arrived in September, a brief break in the high temperatures and humidity is expected this weekend. With no El Niño or La Niña to influence the weather, the long-range fall outlook for Kentucky is for normal temperatures with above average precipitation.
Contact: Greg Goodrich, (270) 745-5986; or Stuart Foster, (270) 745-5983.