South Texas is experiencing a rare break from its typical July heat, as tropical moisture surging from the south is replacing the usual oppressive temperatures with clouds, showers, and thunderstorms. This unseasonal setup is pushing down daytime highs and raising flood risks across Central and South Texas, especially Thursday night into Friday morning.
Mild start to Thursday across San Antonio
The day began under mostly cloudy skies in the San Antonio metro area, with early morning temperatures hovering in the mid-70s°F (around 24°C). Through the morning hours, rain chances remained low—below 20%—but conditions are set to change rapidly as the day progresses.
By noon, scattered showers are expected to build across the region, with San Antonio’s rain chance climbing to 30%, increasing further to about 40% by the late afternoon. Thunder is possible, but the threat of severe weather remains very low. Daytime highs will stay well below average, peaking in the mid to upper 80s°F (29–31°C).
Flooding risk peaks overnight across the Hill Country
Thursday evening into Friday morning brings the highest flood risk to parts of South-Central Texas, particularly the Texas Hill Country. Rain chances in San Antonio are forecast to reach 50 to 60%, and while most areas should see less than 2 inches (5 cm) of rainfall, localized downpours may deliver as much as 5 inches (13 cm).
The flood threat will be isolated, but serious enough to put several communities under watch. Kerrville, Fredericksburg, Boerne, Hondo, and Llano are all included in a Level 2 of 4 risk for excessive rainfall. Meanwhile, the Interstate 35 corridor, including Austin and San Antonio, is under a Level 1 risk, indicating a marginal but notable chance for flash flooding.
Fourth of July weather: umbrellas and humidity
Forecasts for Friday, July 4, have trended wetter. While initial models suggested mostly dry skies, updated data indicates a 30 to 40% chance of rain through the morning and early afternoon across South Texas, including San Antonio. Showers and storms could briefly interrupt holiday plans, but rain chances decrease after sunset, offering a better outlook for fireworks displays.
Despite the clouds and rain, humidity will be intense. Morning temps will start again in the mid-70s°F (24°C), climbing into the upper 80s to near 90°F (31–32°C) by the afternoon. Heat index values may approach the upper 90s°F (36–37°C) due to the thick humidity blanketing the region.
Weekend warming trend returns to San Antonio
As sunshine returns by the weekend, so too will hotter temperatures. San Antonio is projected to reach mid-90s°F (35°C) during the afternoon on Saturday and Sunday, with overnight lows holding steady in the mid-70s°F (24°C).
Looking ahead to next week, the heat dome strengthens once again over South Texas, slowly driving up daytime highs into the upper 90s°F (36–37°C) by Wednesday and Thursday, though most models currently keep the mercury just shy of 100°F (38°C).
