It’s been a hot but calm weekend across South Texas, with most cities — especially around San Antonio — hitting highs in the mid to upper 90s°F (35–37°C). A weak low-pressure system helped bring in patchy clouds, but not enough to cool things down in a significant way.
As of today, Monday, July 21, weather patterns are shifting, and the upcoming week is shaping up to be hotter and drier, thanks to a building high-pressure system pressing in from the west. That system is forecast to dominate the region through Thursday, before a potential tropical disturbance in the Gulf of Mexico becomes the next weather wildcard by the weekend.
Monday begins with clouds blanketing parts of South Texas, keeping morning lows in the mid-70s°F (24°C). Skies will clear by the afternoon, allowing temperatures in San Antonio to climb close to 98°F (37°C), which is a few degrees above average for this time of year. With humidity factored in, it’ll feel more like 102 to 105°F (39–41°C), especially during late afternoon hours.
On Tuesday, the ridge of high pressure will strengthen, pushing temperatures even higher. Early morning lows will sit between 75 and 78°F (24–26°C), with afternoon highs expected to land in the upper 90s°F (37°C). Some neighborhoods, especially on the south side of San Antonio and in rural areas to the southwest, may see their first triple-digit temperatures since late May.
UV levels will spike as well, reaching extreme values between 11 and 12 during early afternoon hours, increasing the risk of skin damage in less than 10 minutes if unprotected.
By Wednesday and Thursday, the weather will follow a similar trend, with intense heat and highs hovering around 97 to 99°F (36–37°C). The dry spell continues, and skies will stay mostly sunny and clear, driven by the overhead high-pressure system.
But all eyes shift to the Gulf of Mexico by Friday and the weekend. A tropical disturbance could begin to take shape, although models remain uncertain about how organized it might become. If a low-pressure center does form, it will have only a short window to develop into anything stronger before possibly impacting the Texas coast.
Right now, moisture from the Gulf could increase shower and thunderstorm chances along the Texas coastline, including areas near Corpus Christi and Galveston, by late Friday into Saturday. However, rain chances in San Antonio remain low, currently projected at only 10 to 20%.
This situation continues to evolve, and weather conditions across South Texas could shift rapidly as we head toward the final weekend of July.
