textproduct: Houston/Galveston

KEY MESSAGES

- A Heat Advisory is in effect through this evening for much of the area.

- Isolated showers and thunderstorms will continue through the week. Higher rain chances expected on Thursday as a surge of moisture moves through.

- High temperatures in the upper to mid 90s expected through Wednesday.

DISCUSSION

Issued at 1256 PM CDT Tue Sep 15 2026

The southwestern edge of a broad mid-level ridge anchored over the Tennessee Valley will continue to provide subsidence over Southeast Texas today and Wednesday, limiting the development of showers and thunderstorms across the region. There will still be sufficient low-level moisture (PWs of 1.7-2.0 inches) and afternoon instability over areas south of the Brazos Valley and Piney Woods region for a few showers and storms to develop during the daytime hours, but coverage is expected to be mostly isolated.

The highs today and Wednesday will continue to range in the mid to upper 90s for most inland areas and in the lower 90s for the coastal locations. The Heat Advisory continues in effect through this evening for heat indices peaking between 106-110 deg F. The heat indices will range between 104-107 deg F on Wednesday. Although it will be below Heat Advisory criteria, make sure to continue to practice heat safety if you plan to work or spend extended periods outdoors. Drink plenty of fluids, stay in an air- conditioned room, stay out of the sun, and try to limit strenuous activities to early morning or evening.

Chances for showers and thunderstorms will increase late Wednesday night through Thursday as a surge of moisture from the northern Gulf moves across the Upper Texas Coast, increasing PWs to 2.0-2.3 inches. The latest NBM run is a bit wetter today compared to yesterday's run, but models continue to shift the mid- level ridge westward into the Arkansas region on Thursday, increasing our mid-level heights from 594 dam to 596-598 dam. Thus, coverage of showers and thunderstorms will likely depend on whether the moisture and instability can overcome the increased subsidence. For this issuance, I have included 45-70% PoPs for areas near and south of I-10 and 20-35% PoPs for the Brazos Valley and Piney Woods. If subsidence cannot be surpassed, then we will likely see lower chances inland with most storms staying generally over the coastal locations and Gulf waters where the highest moisture amounts and least influence of the ridge is. As far as temperatures, the increased cloud coverage and rainfall will help bring the highs back down to the lower to mid 90s on Thursday.

Drier air will move in from the northern Gulf on Friday, decreasing our rain chances to mostly isolated activity near and south of I-10. This trend is expected to continue through the upcoming weekend.

AVIATION

(00Z TAF Issuance) Issued at 625 PM CDT Tue Sep 15 2026

Winds will become light this evening with cloud decks lowering to around 1500-2000ft overnight. Could see some brief instances of MVFR FLs from patchy fog and CIGs, mainly north of I-10 during the early morning hours of Wednesday. CIGs/Fog should clear by the late morning. Isolated showers and perhaps a few storms could develop during the daytime on Wednesday, though coverage is still anticipated to be fairly sparse. Best chances for rain will be along the sea breeze during the mid/late afternoon. Any inland convection that does develop should tapper off into Wednesday evening.

03

MARINE

Issued at 1256 PM CDT Tue Sep 15 2026

Light onshore winds and seas of 2 to 3 feet are expected today and tonight. Winds will become easterly and increase to around 15 kts on Wednesday and 15-20 kts on Thursday. As winds strengthen, seas will rise to 4 to 6 feet by Thursday. Winds relax and seas gradually subside on Friday. Light onshore winds are expected to return during the weekend.

Isolated showers and storms will persist daily, except on Thursday, when scattered to numerous showers and storms are expected as a surge of moisture moves in from the northern Gulf. Stronger winds and higher waves are possible in and near strong storms, along with frequent lightning.

Cotto

PRELIMINARY POINT TEMPS/POPS

College Station (CLL) 76 98 77 96 / 0 10 0 20 Houston (IAH) 79 95 79 93 / 0 20 20 50 Galveston (GLS) 84 91 83 91 / 0 20 60 70

HGX WATCHES/WARNINGS/ADVISORIES

TX...Heat Advisory until 7 PM CDT this evening for TXZ163-164-176>179- 195>200-210>213-226-227-235>238-313-335-338.

GM...None.