So, you're headed to the Alamo City. You’ve probably heard that Texas is hot, but San Antonio is its own beast entirely. Honestly, if you just look at a weather app and see a high of 95°F, you’re only getting half the story. The temperature in San Antonio is a fickle thing that depends as much on the humidity rolling in from the Gulf of Mexico as it does on the actual sun.
It gets swampy. It gets crisp. Sometimes, it does both in the same twelve-hour span.
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The Reality of the San Antonio Summer
Let’s not sugarcoat it: July and August are brutal. You’ll hear locals talk about the "heat dome," and they aren't exaggerating. While the average high sits around 95°F, it’s the heat index that actually dictates your life. In recent years, we’ve seen "feels like" temperatures spike well above 105°F or even 110°F.
I remember walking down to the River Walk in mid-July once, thinking the shade from the cypress trees would save me. Wrong. The River Walk sits below street level, and while it's beautiful, the humidity just hangs there. It’s thick. You don’t just walk; you sort of wade through the air.
Most people assume the heat breaks when the sun goes down. Kinda, but not really. Because of the "urban heat island" effect—all that concrete and limestone in the downtown area—the city holds onto that heat long after dark. It’s common to see midnight temperatures still hovering in the 80s.
When to Actually Visit
If you want the best of the temperature in San Antonio, aim for the "shoulder" windows.
- Late March to April: This is the sweet spot. The wildflowers are peaking, and the highs are usually in the 70s or low 80s. It’s the only time of year you can truly spend all day outside without looking like you just stepped out of a sauna.
- October to early November: The humidity finally starts to back off. You get those legendary Texas sunsets with a bit of a breeze.
The Weirdness of Winter
The coldest month is January, with an average low of about 43°F. But San Antonio winters are erratic. You might have a Monday where it's 75°F and everyone is in shorts at Pearl Brewery, followed by a "Blue Norther" on Tuesday that drops the temperature to 30°F in a matter of hours.
Snow is basically a unicorn here. When it does happen—like the 13 inches in 1985 or the more recent (and much more stressful) freeze of 2021—the city basically pauses. If there’s even a hint of ice on the bridges, stay off the roads. San Antonians are many things, but "winter drivers" is not one of them.
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Real Records to Keep in Mind
- Hottest ever: 111°F (September 5, 2000).
- Coldest ever: 0°F (January 31, 1949).
- Average 100-degree days: Usually around 18 per year, but that number has been climbing lately.
Microclimates and the Hill Country
The temperature in San Antonio isn't even uniform across the city. If you head just twenty minutes north into the Hill Country—places like Boerne or Helotes—it’s often 3 to 5 degrees cooler. The elevation is higher, and there’s more vegetation to break up the heat.
If you're staying downtown near the Hemisfair or the Alamo, you're in the hottest pocket. The limestone buildings are gorgeous, but they act like giant radiators.
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Surviving the San Antonio Thermometer
Basically, if you're coming in the summer, you have to adopt the "Texas Siesta" mindset. You do your outdoor stuff—the Missions, the zoo, the botanical gardens—between 8:00 AM and 11:00 AM. From noon to 5:00 PM, you find a museum with aggressive air conditioning (like the Witte or the SAMA) or a movie theater.
Pro tip: Don't trust the clouds. An overcast day in San Antonio often just means the humidity is trapped, making it feel even more "muggy" than a clear day.
Actionable Advice for Your Trip
- Hydrate beyond water: The humidity makes you sweat more than you realize. Mix in some electrolytes if you're walking the Missions.
- Dress in "Texas Layers": Even if it’s 100°F outside, businesses keep their A/C at a crisp 68°F. You will want a light hoodie or cardigan for indoors.
- Check the Dew Point: If the dew point is over 70, you're going to feel "sticky" no matter what the thermometer says.
- Park in the shade: Even if it means walking an extra block, your car’s interior can hit 140°F in minutes under the Texas sun.
To make the most of your time, keep a close eye on the hourly "feels like" forecast rather than just the daily high. Plan your heaviest physical activities for the early morning hours to avoid the peak heat that typically hits between 3:00 PM and 5:00 PM.