5:55 p.m. update: The National Weather Service has issued a severe thunderstorm watch for parts of South Central Texas, in effect until midnight, Thursday night.

Areas included in the severe thunderstorm watch include Fredericksburg, Johnson City, San Marcos, and Austin. It also includes cities farther north, such as Burnet, Leander, Round Rock, and Georgetown. 

Areas to the south, such as New Braunfels and San Antonio have much lower storm chances and are not included in the watch area.

Heat and humidity have plagued a large part of Central and South Texas over the past few days. Thankfully, a cold front will move through the Lone Star State on Thursday, offering much more comfortable weather by Friday and Saturday.

As the front moves through the region, though, it will bring a chance of scattered severe thunderstorms, some of which will produce large hail and damaging wind gusts. Overall storm coverage will be low, meaning that many areas will stay dry, but the storms that do develop are expected to be very intense.

Where’s the highest chance?

The highest chances of severe storms will stay north of San Antonio. The National Weather Service’s Storm Prediction Center has placed a large region from Central to Northeast Texas under a level 3 of 5 risk for severe weather, which means numerous severe storms are possible.

This area includes the Interstate 35 corridor from Austin to Dallas, as well as East Texas cities like Tyler and Longview. Storms are expected to start after 1 p.m. to 2 p.m. and continue into the evening. Very large hail and a few isolated tornadoes will be possible.

As you move to South Texas, the severe storm threat will be lower in San Antonio, but we still have a slight chance. According to the Storm Prediction Center, San Antonio, Boerne, Kerrville and New Braunfels are under a level 1 to 2 risk of severe weather.

The lower risk level in San Antonio means that storms will be more isolated, so overall storm chances would even lower. San Antonio’s overall chance of storms is only 10 to 20%, meaning 80 to 90% of the region will stay dry. However, if a storm does develop near Bexar County, large, damaging hail will be possible.

The best chance for storms in Central and South Texas will be in the late afternoon and evening, generally between 5 p.m. and 9 p.m.

An especially hot day coming

No matter if San Antonio encounters thunderstorms or not, it’s going to be another hot and humid day across South Texas. Expect a muggy start to the morning with cloudy skies, patchy fog and temperatures hovering in the mid-70s.

By mid-morning, clouds will start to break and temps will rise quickly. San Antonio will be in the upper 80s to near 90 degrees by noon. High temps are expected in the mid- to upper 90s by the late afternoon, but the humidity will make things feel much worse.

Heat index values, or “feels like” temps that account for humidity’s effect on the body, are expected to reach between 100 and 105 degrees for the entire afternoon. This is a dangerous level of heat, so avoid high levels of strenuous activities if possible. Be sure to stay hydrated, wear loose-fitting clothing, and take plenty of breaks away from the heat.

Temps turn cooler

The cold front moving through South Texas late Thursday will shift the wind direction and usher in some cooler air from the north. Friday is not going to be chilly by any stretch of the imagination, but it won’t be as hot. Morning low temperatures will be near 70 degrees, and highs will rise to only the mid-80s under partly cloudy skies.

Mostly cloudy skies return Saturday, which will help to bring temperatures down a few more degrees. Lows will drop to the upper 60s and highs temps will reach the low 80s, several degrees below average for mid-May.

There is a 20% chance of a few showers and storms in San Antonio on Saturday, but higher rain chances will arrive on Sunday.