Heat achievement unlocked: San Antonio has just hit 100 degrees for the first time in 2026

At 3:40 p.m. Wednesday afternoon, the temperature at San Antonio International Airport reached 100 degrees, hitting the triple-digit mark for the first time in 2026. This comes about four weeks later than normal, as San Antonio's average date for its first 100-degree day comes on June 26.

It feels even hotter outside because of elevated humidity levels across South-Central Texas. San Antonio heat index values were near 108 degrees Wednesday afternoon, and they had been expected to stay there for the next several hours.

Evening temperatures will fall very slowly in San Antonio. Even by 8 p.m., San Antonio will likely still be near 97 degrees, with heat index values of around 105.

A heat advisory is in place for much of the region, including San Antonio, New Braunfels, San Marcos and the Texas Hill Country. Meanwhile, Austin is under an extreme heat warning, as heat index values there could reach up to 115 degrees.

Hitting 100 degrees holds less of a meteorological significance than a public health one. Temperatures in the triple digits are more dangerous because everyone, not just the old or very young, becomes much more susceptible to heatstroke or heat exhaustion.

To remain safe in the heat, limit time outdoors through Wednesday afternoon and evening. If you must be outside, drink plenty of water, wear loose-fitting and light-colored clothing, and take frequent breaks in air-conditioned spaces. Also, never leave children or pets unattended in a vehicle, even for a minute or two.

More triple-digit temps coming

The San Antonio area is likely to reach close to the 100-degree mark again on Thursday. Then, as Tropical Storm Bertha sends moisture into the region late Thursday and into Friday, temperatures are expected to fall back into the mid-90s.

Triple-digit temperatures will likely return to South-Central Texas by the middle of next week. Then, long-range weather models suggest that extreme heat may continue through the first week of August.

Average number of 100-degree days

Triple-digit temperatures have become more common in San Antonio over the past couple decades.

During the 20 years between 2006 and 2025, San Antonio has averaged 27 days per year with high temperatures of at least 100 degrees. However, in the 20 years preceding (1986 to 2005), San Antonio averaged just 12 days per year at 100 degrees or more.

San Antonio's greatest number of 100-degree days came in 2023, when a staggering 75 days topped out at 100 degrees or higher. Only three other years in history - 2009, 2011, and 2022 - have resulted in at least 50 triple-digit days.

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