Tornadoes are a reality in San Antonio, Texas, and the surrounding metropolitan area. A tornado is a violently rotating column of air extending from a thunderstorm to the ground, and atmospheric conditions over South Central Texas occasionally align to produce them. While the region is not the most active part of the country for these events, the risk is persistent. Understanding the frequency and meteorological factors helps prepare residents for severe weather.
Historical Frequency in the San Antonio Region
The historical record for Bexar County, which contains San Antonio, shows that tornadoes occur with a relatively low frequency but can be severe. Since documentation began in 1953, the county has confirmed approximately 71 tornadoes, which averages out to about one confirmed twister per year. This average, however, is not spread evenly, with periods of heightened activity followed by longer stretches with no recorded events.
The majority of these tornadoes are considered weak, with 56 of the 71 events rated at the bottom of the Enhanced Fujita (EF) scale as an EF0 or EF1. These weaker twisters cause minor to moderate damage, such as broken tree limbs or superficial structural harm. Stronger tornadoes have also touched down, with 13 events reaching an EF2 rating, capable of causing considerable damage.
Two specific historical events demonstrate the potential for greater danger. In April 1953, an F4 tornado—the strongest ever recorded in the county—struck the Helotes area in the northwestern part of Bexar County, resulting in two fatalities. More recently, in February 2017, an outbreak produced an EF-2 tornado that caused significant damage to homes in the Ridgeview and Alamo Heights subdivisions.
An unusual event occurred in September 1988 when the remnants of Hurricane Gilbert spawned multiple tornadoes in the area, including an F2 that hit Kelly Air Force Base. These incidents confirm that while strong tornadoes are rare, the potential for them to impact the metro area remains.
San Antonio’s Climatological Risk Profile
San Antonio’s location places it on the southwestern edge of “Tornado Alley,” which has higher frequency in the northern parts of Texas. The city’s risk is primarily driven by its proximity to the Gulf of Mexico, only about 125 miles away. The constant influx of warm, moist air from the Gulf provides the atmospheric fuel necessary for severe thunderstorm development.
The city is situated along the Balcones Escarpment, a geological fault line that separates the Texas Hill Country from the flatter Coastal Plain. While this feature is more famous for contributing to flash flooding in the region, it also plays a role in storm dynamics. The lifting of moisture-rich air over the escarpment can help initiate or intensify thunderstorms that may eventually produce tornadoes.
Meteorologically, the risk increases when cold fronts push south from the Plains and collide with the warm, humid air mass over South Central Texas. This clash of air masses creates atmospheric instability and wind shear, which are the fundamental ingredients for supercell thunderstorms and rotating updrafts. Unlike areas further north, San Antonio’s environment sees a lower frequency of the most favorable conditions, which explains the lower annual tornado count.
Research suggests that while the frequency of tornado-generating atmospheric conditions may be decreasing in this part of the Southern Plains, the risk has not diminished. San Antonio’s rapid population growth and expanding development mean that even a rare, weak tornado now has a much higher chance of impacting people and property. The city’s vulnerability to severe weather remains a concern.
Peak Seasonality for Severe Weather
Severe weather in the San Antonio region, including the tornado threat, follows a seasonal pattern. The primary season for severe thunderstorms and tornadoes occurs during the spring months, specifically peaking in April and May. This is when the interaction between Gulf moisture and frontal systems from the north is most common and vigorous.
May stands out as the most active month for severe weather reports across the state of Texas. Activity begins to rise in March, intensifies through April, and reaches its height in May before the typical summer heat and high-pressure systems start to stabilize the atmosphere. By June, the risk begins to drop significantly as the summer pattern takes hold.
The region also experiences a secondary, though less intense, severe weather season in the fall, particularly in October. During this transitional period, the polar jet stream shifts southward, again setting the stage for a clash between cold, dry air and the lingering warm, humid air from the Gulf. This secondary peak provides another window for tornado development, although the frequency is substantially lower than during the spring.