San Antonio woke up under clear skies and a crisp chill on Wednesday, March 18, 2026, with temperatures sitting in the mid 40s. By this afternoon, strong March sunshine and a building thermal ridge over South Central Texas are expected to bump those readings into the upper 70s, a warm-up more in line with late spring than the tail end of winter.
Warm Spell And Record Threats
The National Weather Service Austin/San Antonio is flagging the potential for record highs from Friday through Sunday, March 20 to 22, 2026. Forecast highs are set to climb from near 79°F on Wednesday to about 84°F on Thursday, then near 89°F on Friday and into the low 90s on both Saturday and Sunday. At the time of the forecast, there were no watches or warnings in effect for the region, but forecasters are keeping a close eye on the heat.
Fire Weather Concerns
As temperatures climb, lower nighttime humidity and daytime mixing are expected to push minimum relative humidity values into the teens and 20s late this week. That dry air raises the risk of rapidly spreading brush fires across the more parched parts of the metro area, especially west of I-35. Winds are projected to stay generally light for much of the period, but a burst of stronger south winds along the Rio Grande on Sunday could bring near critical fire weather conditions there. Residents using outdoor grills, burn barrels or tending piles of yard debris should take extra care with any spark this weekend.
What To Know For The Weekend
If you are planning to be outside, aim for mornings or evenings when it will be coolest, and keep water on hand for both people and pets during the hottest part of the day. A burn ban remains in effect for unincorporated parts of Bexar County, so check with the Bexar County Fire Marshal for current restrictions before lighting any open flame. Secure yard debris, keep grills well away from dry grass or brush, and remember that even a single stray ember can spread quickly under low humidity.
Sunny, dry conditions are expected to hold into next week, with daytime temperatures staying well above seasonal averages. Before locking in weekend or early week plans, keep an eye on updated forecasts from the National Weather Service and advisories from local officials.
