Typical of the Deep South, Tuscaloosa experiences a humid subtropical climate with four distinct seasons. The Gulf of Mexico heavily influences the climate by supplying the region with warm, moist air. During the fall, winter, and spring seasons, the interaction of this warm, moist air with cooler, drier air from the North along fronts creates precipitation. These fronts usually move from west to east as they track along the jet stream. Notable exceptions occur during hurricane season, where storms may move from due south to due north or even from east to west during land-falling hurricanes. The interaction between low- and high-pressure air masses is most pronounced during the severe weather seasons in the spring and fall. During the summer, the jet stream flows well to the north of the southeastern U.S., and most precipitation is consequently convectional, i.e., caused by the warm surface heating the air above.
Severe thunderstorms can bring damaging winds, large hail, and occasionally tornadoes. An F4 tornado struck Tuscaloosa County in December 2000, killing eleven people. Tuscaloosa was struck by an F2 tornado in January 1997, which resulted in the death of one person. In April 2011, two tornadoes in a span of twelve days hit the city, the first being an EF3 on April 15, and the second and more devastating being an EF4 on April 27, when more than 50 deaths resulted. The city suffered considerable infrastructure damage.
Winter lasts from mid-December to late-February; the daily average temperature in January is 44.7 °F (7.1 °C). On average, the low temperature falls to the freezing mark or below on 46 days a year, and to or below 20 °F (−7 °C) on 4.4 days. While rain is abundant (January and February are on average the wettest months), measurable snowfall is rare, with most years receiving none and the average seasonal snowfall amounting to 0.7 inches (1.8 cm). Spring usually lasts from late-February to mid-May, becoming drier as the season progresses. Summers last from mid-May to mid-September, and the July daily average temperature is 81.7 °F (27.6 °C). There are 71–72 days of 90 °F (32 °C)+ highs annually and 3.5 days of 100 °F (38 °C)+ highs. The latter part of summer tends to be drier. Autumn, which spans from mid-September to early December, tends to be similar to spring in terms of temperature and precipitation.
The highest recorded temperature at the Tuscaloosa Regional Airport was 107 °F (42 °C) on July 29, 1952 and August 10, 2007, while the lowest recorded temperature was −1 °F (−18 °C) on January 21, 1985.