Lexington is in the northern periphery of the humid subtropical climate zone , with hot, humid summers and moderately cold winters with occasional mild periods; it falls in USDA hardiness zone 6b. The city and the surrounding Bluegrass region have four distinct seasons that include cool plateau breezes, moderate nights in the summer, and no prolonged periods of heat, cold, rain, wind, or snow. The monthly daily average temperature ranges from 33.9 °F (1.1 °C) in January to 76.7 °F (24.8 °C) in July, while the annual mean temperature is 56.3 °F (13.5 °C). On average, 25 days of 90 °F (32 °C)+ highs occur annually and 23 days per winter where the high is equal to or less than freezing. Annual precipitation is 49.84 inches (1,270 mm), with the late spring and summer being slightly wetter; snowfall averages 14.5 inches (37 cm) per season. Extreme temperatures range from −21 °F (−29 °C) on January 24, 1963, to 108 °F (42 °C) on July 10 and 15, 1936.
Lexington is recognized as a high allergy area by the Asthma and Allergy Foundation of America.