If you’ve lived in San Antonio for more than a week, you know the drill. You walk outside in the morning and it’s a crisp 50 degrees, then by lunch, you’re sweating through your shirt in 90-degree humidity. It’s chaotic. People like to joke that the city has four seasons—sometimes all in the same afternoon. But when you actually dig into San Antonio weather history, you realize the city isn't just "hot." It’s a place of extremes that have shaped everything from the architecture of the Pearl District to the way the River Walk was engineered.
San Antonio sits right on the edge of a humid subtropical zone and the semi-arid brush country. Basically, it’s a geological and atmospheric battleground. To the north, you have the Balcones Escarpment—the start of the Hill Country—which acts like a literal wall. This "wall" often traps moisture coming up from the Gulf of Mexico, leading to some of the most intense flash flooding in the United States. It’s a weird, wild history.
The Floods That Changed Everything
Most folks visit the River Walk and think it’s just a cute place for margaritas. Wrong. It’s a flood control project.
In September 1921, a massive disaster hit. A tropical depression stalled out over the Olmos Basin. The water came down fast. Like, terrifyingly fast. The downtown area ended up under nine feet of water in some spots. More than 50 people died. This single event is arguably the most important moment in San Antonio weather history because it forced the city to choose: pave over the river or save it.
Initially, the plan was to turn the bend of the river into a concrete sewer. Thankfully, the San Antonio Conservation Society fought back. They ended up building the Olmos Dam and the bypass channel that keeps the tourist areas dry today. If that 1921 storm hadn't happened, the city would look completely different. We wouldn't have the iconic stone bridges or the cypress trees lining the banks; we’d have a massive drainage ditch.
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Ice, Snow, and the "Big Freeze" Anomalies
San Antonio is famous for 100-degree streaks. We've had summers where the triple digits just won't quit—like 2023, which was basically a months-long oven. But the real stories in the archives are the ones involving ice.
Take February 2021. Winter Storm Uri. It wasn't just a "cold snap." It was a systemic failure triggered by a historic temperature drop to 9 degrees Fahrenheit. For a city that considers 40 degrees "freezing," this was apocalyptic. It stayed below freezing for over 100 consecutive hours. People were wrapping their pipes in pool noodles and blankets.
But if you look back further, 1985 was the true snow king. In January of that year, San Antonio got hit with 13.2 inches of snow. Imagine that. The Alamo covered in over a foot of white powder. It paralyzed the city. People were skiing down the hills in Brackenridge Park. Most locals today can't even fathom a foot of snow, but the records prove it happened. It’s the kind of outlier that makes predicting Texas weather a nightmare for meteorologists at the National Weather Service.
Heat Waves: Surviving the 100-Degree Marathons
Let's be real: heat is the defining characteristic of this region. But "hot" is an understatement. The record high stands at 111 degrees, set in September 2000 and tied again more recently.
What’s interesting about San Antonio weather history is how the heat has shifted. It’s not just getting hotter; the nights aren't cooling down like they used to. This is the "Urban Heat Island" effect. All the asphalt on Loop 1604 and I-10 soaks up the sun and radiates it back out at 2:00 AM.
Why the humidity feels different here
A lot of people compare us to Houston. Don't. Houston is a swamp. San Antonio is a "dry-ish" heat that gets humid when the wind shifts out of the southeast.
- When the wind comes from the West (Big Bend/Mexico), the humidity drops to 10%, and your skin feels like parchment paper.
- When the wind comes from the South (Gulf of Mexico), the dew point spikes to 75, and you feel like you're breathing underwater.
The 1998 "Flood of the Century"
You can't talk about local climate without mentioning October 1998. This was a "perfect storm" scenario. Two systems collided right over South Central Texas. Some areas near New Braunfels and San Antonio saw 20 to 30 inches of rain in less than two days.
I remember the footage of the Guadalupe and San Antonio rivers just swallowing houses. It was a sobering reminder that while we worry about drought and Stage 3 water restrictions, the real threat in our history has always been water. The Edwards Aquifer—our main water source—can go from record lows to "flooding the caves" in a matter of weeks. It’s a boom-and-bust cycle that has dictated how the city grows. We build neighborhoods with massive detention ponds for a reason.
Misconceptions About the "Tornado Alley" Label
People often ask if San Antonio is in Tornado Alley. Technically? No. Practically? We get them.
In February 2017, a series of tornadoes (EF-0 to EF-2) tore through the North Side, specifically around the Quarry and Linda Drive. It was weird because it happened at night. Usually, we think of tornadoes as a "Great Plains in the afternoon" kind of thing. But in our neck of the woods, tornadoes are often embedded in "squall lines." You don't see a funnel; you just see a wall of rain and wind.
San Antonio weather history shows that while we don't get the massive F5 monsters like Moore, Oklahoma, we get frequent, smaller spins that can still rip a roof off a Starbucks in seconds.
How to Actually Use This Info (Actionable Insights)
If you're moving here, visiting, or just trying to survive another August, stop looking at the "High/Low" on your phone app. It's lying to you.
Watch the Dew Point, Not the Temp
If the dew point is over 70, you’re going to be miserable regardless of the temperature. If it's below 55, it’s a beautiful day, even if it’s 90 degrees out. That’s the "desert" side of San Antonio weather history creeping in.
Landscaping for the Reality of Extremes
Stop planting lush, green grass that belongs in Kentucky. History shows us that we will have a multi-year drought, followed by a hard freeze, followed by a flood.
- Use Texas Sage (Cenizo). It’s literally nicknamed the "Barometer Bush" because it blooms right before it rains.
- Plant Mountain Laurels. They survive the 100-degree sun and the 10-degree freezes.
Understand the Flash Flood Alley
San Antonio is part of the most flash-flood-prone region in North America. Never, ever drive through a low-water crossing if there’s water on the road. "Turn around, don't drown" isn't just a cheesy slogan; it's a rule written in the blood of the 1921 and 1998 disasters.
The Best Time to Visit
Forget the summer. Honestly. If you want the best of what our climate history offers, come in late October or early November. The humidity has usually broken, the "Cold Front" season has started, and you get those crystal-clear blue Texas skies. Or try late March, but be prepared for the "Oak Pollen" blizzard that turns every car yellow.
The weather here isn't something you just observe; it's something you negotiate with. It’s a history of resilience—of a city that learned to build dams instead of burying its river and a community that knows how to find shade when the sun tries to claim the streets. Keep a jacket in your trunk and an umbrella in the backseat. You’ll need both by Tuesday.
Next Steps for San Antonio Residents:
- Check your home's proximity to the 100-year floodplain via the SARA (San Antonio River Authority) digital maps; many historical flood zones have expanded.
- Install a smart thermostat to manage the "Urban Heat Island" spikes, which are historically most aggressive between 4:00 PM and 7:00 PM.
- Winterize your external plumbing by November, regardless of the forecast—history shows our most damaging freezes often arrive with less than 48 hours of warning.