textproduct: Austin/San Antonio

KEY MESSAGES

- Hazardous heat continues Thursday across all of south central Texas.

- Rain chances across portions of the area this evening through early Sunday, with locally heavy rainfall possible.

- The heat and humidity continue this weekend into early next week, with perhaps a brief break on Saturday.

UPDATE

Issued at 907 PM CDT Thu Jun 18 2026

As temperatures cool, the heat indices have mostly dropped below warning and advisory criteria. We have allowed the Excessive Heat Warning and the Heat Advisory to expire. It's still unusually hot, so please exercise caution.

There is still too much uncertainty about tomorrow to issue any new products. Temperatures should be cooler, but the they could stay high enough across the south to warrant an advisory. We'll make a decision as the latest forecast data comes in.

SHORT TERM

(Tonight through Friday night) Issued at 207 PM CDT Thu Jun 18 2026

Morning clouds are long gone, with only some scattered cumulus clouds noted from the coastal plains region northward into the Highway 77 corridor. With plenty of sunshine and continued south to southeasterly flow in the lower levels, dangerous heat and humidity remain in place across all of south central Texas this afternoon and early evening. Based on recent trends, we do not plan on any changes to the current heat headlines. Warm and humid conditions persist this evening and tonight with lows in the upper 70s to lower 80s. We will need to monitor a couple of areas for convective trends this evening. The first area will be over the Rio Grande plains and southern Edwards Plateau where recent observations show a dryline located just east of Dryden. At least a few of the hi-res models develop some convection near the dryline late this afternoon/early evening. The other area to monitor will be farther north across west central Texas where a cold front drops southward this evening and will likely initiate some convection during the late evening into early morning hours. Some of the models manage to show an outflow boundary dropping southward from this convection into the Hill Country and possibly I-35 corridor early tomorrow morning. If storms manage to develop out west and/or initiate along the southward moving outflow boundary, we could see some locally heavy rainfall develop given the more than adequate atmospheric moisture and instability. The latest WPC heavy rainfall outlook now shows a Level 1 and 2 of 4 risk for the southern Edwards Plateau and Hill Country for today into tonight.

The forecast for tomorrow is rather tricky as much will depend on what occurs this evening and tonight. If storms manage to develop early in the day, we could see enough time for the atmosphere to recover and allow for more convection to develop Friday afternoon and evening as a weak upper disturbance moves into the central portion of Texas. Again, some locally heavy rainfall could develop in this regime and WPC shows a level 2 of 4 risk across most of of south central Texas, with a level 1 of 4 risk over the coastal plains. With regards to the temperatures on Friday, much will depend on what occurs this evening and overnight. Any convection and outflow boundaries will have an impact on the high temperature on Friday. We have decided to hold off on the issuance of a Heat Advisory for now, but will need to monitor areas along and east of the Interstate 35 corridor.

LONG TERM

(Saturday through next Thursday) Issued at 207 PM CDT Thu Jun 18 2026

A lingering upper level disturbance on Saturday along with an increase in cloud cover may keep highs on Saturday in the upper 80s to mid 90s for most areas. We'll keep some rain chances in the forecast for most areas, with slightly better chances expected from the Hill Country into the I-35 corridor and coastal plains region. The weak upper disturbance will move away from the region on Sunday, resulting in a drying trend along with temperatures warming a few degrees. Afternoon heat indices will need to be monitored for areas along and east of Interstate 35 on Sunday.

Mid-level ridging builds and strengthens along the Arizona and Mexico border Monday and onward through the end of the long term forecast period with a broad trough lingering in the Southeastern CONUS. This would keep South-Central Texas within a west- northwesterly to northwesterly mid-level flow. While this forecast remains generally rain free, we'll continue to monitor for any convective chances to our north-northwest and any approaching activity and/or outflow that could try to approach. A persistent south to southeasterly flow will help to keep temperatures holding above average with elevated heat indices with the humidity also factored in. Afternoon highs will reach into the mid 90s with the peak heat indices reaching into the 105 to 110 degree range for areas along and east of the I-35 corridor and over the Rio Grande Plains. Overnight lows will be very warm and humid in the mid to upper 70s with returning low stratus most nights from late each overnight into each morning. We'll analyze any need for heat products as this period gets closer in time.

AVIATION

(00Z TAFS) Issued at 648 PM CDT Thu Jun 18 2026

VFR conditions are forecast for the local area sites through late this evening. Then, around 05Z Friday, MVFR cigs are forecast to develop along the I-35 terminals and stay through late Friday morning. For KDRT, things are different as we monitor a cluster of storms over northeast Mexico and another one over Crockett County. The cluster of Mexico could get closer and push over the Rio Grande within the next few hours. Therefore, the PROB30 group for KDRT through this evening. Otherwise, high clouds are forecast to linger around KDRT with low clouds (MVFR) developing Friday morning. MVFR cloud deck remains over the I-35 sites through early Friday afternoon before VFR cigs return. A line/outflow boundary is forecast to push from the Hill Country into the I-35 corridor Friday afternoon and evening. Showers and storms are likely to have an impact over the those terminals through the period. A southeast flow 5 to 10 knots is forecast to dominate for most of forecast period with gusts up to 25 knots associated with storms.

PRELIMINARY POINT TEMPS/POPS

Austin Camp Mabry 79 94 78 92 / 20 30 40 50 Austin Bergstrom Intl Airport 79 93 78 92 / 10 30 40 50 New Braunfels Muni Airport 79 93 77 91 / 10 30 40 50 Burnet Muni Airport 77 91 75 91 / 30 40 40 40 Del Rio Intl Airport 82 97 77 95 / 30 40 40 10 Georgetown Muni Airport 78 92 77 91 / 20 40 40 50 Hondo Muni Airport 79 93 76 91 / 20 20 50 30 San Marcos Muni Airport 79 93 77 92 / 10 30 40 50 La Grange - Fayette Regional 81 93 79 91 / 0 30 40 50 San Antonio Intl Airport 80 93 78 91 / 10 20 40 50 Stinson Muni Airport 79 93 78 92 / 10 20 50 50

EWX WATCHES/WARNINGS/ADVISORIES

None.