Chattanooga, like much of Tennessee, has a four-season humid subtropical climate . Winter days are usually mild, but most years have at least one day (average 3.2) where the high remains at or below freezing. Snowfall is highly variable from year to year. 11 inches (28 cm) were recorded between January 9–10, 2011. Summers are hot and humid, with a July daily mean of 80.0 °F (26.7 °C) and 52 days annually with 90 °F (32 °C) or greater temperatures. Chattanooga is the sixth fastest warming city in the United States due to climate change.
Average annual precipitation is over 52 inches (1,300 mm). On average, November through March represents an extended relatively wet period, because of Chattanooga’s frequent placement (in the winter season) in a zone of conflict between warm, moist air from the Gulf of Mexico and cold, dry air from Canada, amplified by jet-stream energy and abundant Gulf moisture. July presents a secondary maximum in precipitation, due to frequent thunderstorm activity. Despite the mountains that surround the city, Chattanooga has been affected by tornadoes. These tornadoes include the 2011 Super Outbreak, which impacted the city and nearby locations, including Apison and Cherokee Valley in Catoosa County, Georgia, where fifteen people died, eight in Apison and seven in Cherokee Valley. An EF3 tornado struck southeastern portions of Chattanooga on the night of April 12, 2020, and caused significant damage and three fatalities.