So far this warm season we have managed to keep the large bubbles of high pressure, which bring dry weather and heat, away from the Ohio Valley region. The result has been near normal precipitation as well as periods of below normal temperatures. The forecast for Sunday into the next work week indicate we may see our first 90 degree temperatures. So how unusual is it to get to mid June and not hit 90 degrees? The average first date for that threshold at Louisville is June 1st, with the latest first date occurring on July 14th, way back in 1915. We had a later than normal start even last year at Louisville, with the first 90 degree day occurring on June 12th. The last time we waited until July to hit that mark was back in 2004, when the first date was July 10th.
As for the Lexington area, the average first date for 90-degree temperatures is June 14th. However, they do not always hit 90 degrees, with that same 2004 cool year being the last time Lexington did not hit reach 90 all summer.
The first date for Bowling Green is much earlier than for the other sites, May 20th, with the latest first date being June 26th. The last time they were later than mid June was back in 2003, when they hit 90 on June 25th.
Below is an ensemble forecast model, which indicates why we may see our first 90s next week. One of those bubbles of high pressure will build in across the Deep South by Monday afternoon. We will not be right under it, so isolated to scattered thunderstorms are possible each day of the next work week. Another factor that could keep us from reaching 90 degrees is the vegetation across the region, which is still fairly green thanks to near normal precipitation so far this year.