Another August scorcher, San Antonio. If you're planning a midday long run, you've got another thing coming. Today's heat advisory is no joke.
- Heat Advisory until 7 PM. Expect temperatures up to 105°F with heat index values hitting 110°F. Unless you're trying to win a Darwin Award, keep your strenuous outdoor activities to the absolute earliest morning or late evening. Your body simply cannot cool itself efficiently in this kind of oven.
- "Good" AQI? Don't get complacent. While the official Air Quality Index is sitting at 45 (which is technically "Good" by EPA standards), some forecasts are flagging San Antonio with "Ozone/PM2.5" and even "Poor" air quality for sensitive groups today. If you've got asthma, allergies, or just easily irritated lungs, you'll feel it, especially with that triple-digit heat baking everything. A "Good" AQI is under 50, but anything between 51 and 100 is considered moderate, and some sensitive folks feel it even below that.
- Moderate Pollen. Just what we need. Another layer of irritation for your respiratory system.
- Trail Closures & Critters: Helton Nature Park is entirely shut down today through Friday for paving work. So, scratch that from your list. And if you're thinking of hitting the Mission Reach, be aware of reported active wasp nests near the pavilion at Confluence Park. Nobody needs a side of stings with their run.
Environmental Breakdown
| Pollutant Category | Level |
|---|---|
| Pollen | Moderate |
| Air Quality Index | 45 |
| Dominant Pollutant | Ozone/Other |
| Temperature | 26.8°C (80.2°F) |
| Condition | Clear |
DANGER: Extreme Heat Advisory!
The National Weather Service has issued a Heat Advisory for Bexar County until 7 PM CDT tonight, August 26. Highs are expected to reach 105°F with a heat index up to 110°F. Heat-related illnesses are a real threat. Seriously, don't be a hero.
Air Quality for Sensitive Groups
Even with the "Good" AQI reading, ground-level ozone and fine particulate matter (PM2.5) are present. If you have any respiratory issues, you might find prolonged outdoor exposure uncomfortable. Consider an indoor workout, or stick to easy activities in the early morning.
Hydration is Non-Negotiable
With this heat, you're losing fluids faster than you think. Carry more water than you believe you need, and don't wait until you're thirsty to drink. Pre-hydrate, hydrate during, and re-hydrate after. This isn't just a suggestion; it's survival.
Mind Your Trails
If you're out near Confluence Park on the Mission Reach, keep an eye out for those wasp nests. And again, Helton Nature Park is a no-go for the next couple of days. Plan your routes accordingly and check the City of San Antonio Parks and Rec site for any other localized closures or issues before you head out.
Data grounded with KENS5.com, TCEQ, MySA, and San Antonio River Authority from August 25-26, 2026.