Louisville has a humid subtropical climate , typical of the Upper South, and is located in USDA hardiness zones 6b and 7a. Spring-like conditions typically begin in mid-to-late March, summer from mid-to-late-May to late September, with fall in the October–November period. Seasonal extremes in both temperature and precipitation are not uncommon during early spring and late fall; severe weather is not uncommon, with occasional tornado outbreaks in the region. Winter typically brings a mix of rain, sleet, and snow, with occasional heavy snowfall and icing. Louisville averages 4.5 days with low temperatures dipping to 10 °F (−12 °C); the first and last freezes of the season on average fall on November 2 and April 5, respectively. Summer is typically hazy, hot, and humid with long periods of 90–100 °F (32–38 °C) temperatures and drought conditions at times. Louisville averages 38 days a year with high temperatures at or above 90 °F (32 °C). The mean annual temperature is 58.2 °F (14.6 °C), with an average annual snowfall of 12.7 inches (32 cm) and an average annual rainfall of 44.9 inches (1,140 mm).
The wettest seasons are spring and summer, although rainfall is fairly constant year round. During the winter, particularly in January and February, several days of snow can be expected. January is the coldest month, with a mean temperature of 34.9 °F (1.6 °C). July is the average hottest month with a mean of 79.3 °F (26.3 °C). The highest recorded temperature was 107 °F (42 °C), which last occurred on July 14, 1936, and the lowest recorded temperature was −22 °F (−30 °C) on January 19, 1994. In 2012, Louisville had the fourth-hottest summer on record, with the temperature rising up to 106 °F (41 °C) in July and the June all-time monthly record high temperature being broken on two consecutive days. As the city exemplifies the urban heat island effect, temperatures in commercial areas and in the industrialized areas along interstates are often higher than in the suburbs, often as much as 5 °F (2.8 °C).