Lexington 10 Day Weather. 1  Thursday:The Lexington forecast for Aug 24 is 83 degrees and Overcast. 2  Friday:The Lexington forecast for Aug 25 is 85 degrees and Sunny. 3  Saturday:The Lexington forecast for Aug 26 is 84 degrees and Overcast. 4  Sunday:The Lexington forecast for Aug 27 is 80 degrees and Sunny.