Monthly Climate Summary
August 2009

After a stormy start that featured record-breaking rainfall in Louisville, August 2009 settled into a cool and mostly dry weather pattern. A cool and stormy first few days of August culminated in a downpour on the 4th that featured rainfall rates typically found in the tropics. Up to seven inches of rain fell in an hour in parts of the Louisville metro area, which caused millions of dollars of damage to notable landmarks such as Churchill Downs racetrack, the University of Louisville campus, and the downtown public library. Hundreds of homes were damaged by the resulting floodwaters and more than 20,000 homes lost power. While hundreds of people were rescued by various emergency agencies, remarkably there were no fatalities or injuries from the flooding. Heavy rain that ranged from two to four inches also fell on the 4th in several other counties along the Ohio River as well as in more isolated thunderstorms in Butler County and near Paducah. Communities that received heavy rainfall from the storms on the 4th ended up wetter than normal for August while most of the rest of the state, most notably south-central Kentucky, ended up much drier than normal.

While the cold fronts that moved across Kentucky in June and July seemed to always produce soaking downpours, the cold fronts in August tended to underperform. This underperformance occurred to a large extent from the 14th to the 20th, when thunderstorms were in the forecast each day but only trace amounts to a few tenths occurred in most locations. The main exceptions were Hopkins County and the Bluegrass region, where isolated thunderstorms produced flash flooding on the 18th. Temperatures remained below normal for a second straight month, although not to the extent of the near-record cool of July. Most locations averaged around one degree below normal, with notable cold stretches from August 22nd-24th and the 30th-31st. These cool periods featured high temperatures in the 70s with nighttime temperatures that fell into the lower 50s, leading to a few record lows. The only severe weather during August occurred with the thunderstorms on August 4th. Minor damage occurred in Christian County from a pair of brief EF0 tornadoes north of Hopkinsville. For the summer as a whole, 2009 will be remembered for being cool and wet. Summer 2009 was the 3rd wettest for Louisville and Jackson and the 4th wettest for Bowling Green. The near-record cool weather of July and the continued cool of August allowed 2009 to be the coolest summer since 2004. The persistent cool and wet weather has delayed the corn crop across the state by three weeks, leading some agricultural experts to be concerned about the potential damage to crops should there be an early frost this fall.