Area Forecast Discussion

KEY MESSAGES

Updated at 527 PM CDT Sat Sep 19 2026

- Daily low medium chances of rain return next Monday and become region-wide by next Tuesday.

- Temperatures remain warm but ease off a few degrees from widespread areas of low 100s along/west I-69 E to mostly upper 90s by Tuesday.

- Extreme risks of heat-related illnesses (level 4/4) are likely to continue for portions of the RGV/Rio Grande Plains while the rest of the region experiences moderate to major risks (level 2/4 and 3/4).

- A moderate risk of life-threatening rip currents continues through tonight.

DISCUSSION

Issued at 1204 PM CDT Sat Sep 19 2026

Will continue to see a somewhat unsettled weather pattern through the forecast period. Aloft, high pressure will prevail over Deep South Texas which will help suppress rain chances through the weekend. While we could still see some isolated showers and thunderstorms this weekend, will be limited to 15% and be mainly along the coast.

Rain chances increase as we head into the work week as a cold front moves into central Texas. The moisture pooling ahead of this boundary will increase the chances of showers and thunderstorms, especially along the seabreeze. As we head into to late week models are hinting at a tropical wave moving west which help to keep rain chances in the forecast, especially each afternoon. Best rain chances will be Friday (up up 60%), primarily along the coast into the mid-Valley.

Heat Risk will remain Moderate to Extreme over the next week, though increased cloud cover and/or showers and thunderstorms could bring a little relief. Temperatures will still remain above normal into mid to upper 90s to low triple digits though by Thursday and Friday, could struggle to reach the triple digits with the excess cloudcover and rain chances. Heat indices will peak each afternoon between 105-110 degrees.

There is a moderate risk of rip currents at area beaches. The strongest and most life threatening rips currents often occur near jetties and piers. Use caution if entering the water.

AVIATION

(00Z TAFS) Issued at 534 PM CDT Sat Sep 19 2026

Fair weather and excellent flying conditions...outside of the usual afternoon thermals for smaller aircraft...is the story through late Sunday afternoon. A quiet evening on tap with the usual early evening gusty easterlies settling down to near-calm conditions under mainly clear skies...save for passing few- scattered MVFR fair weather cumulus.

For Sunday morning, expect another period with Gulf and northeast Mexico towering cu and a few cumulonimbus...but the aerodromes should be free of significant clouds to start along with light winds. Like the previous few days, expect a period of cumulus congestus at Brownsville and Harlingen by mid to late morning, continuing through noon or so before the cumulus flattens and pushes inland with mainly clear skies after 2-3 PM. McAllen will start clear and continue through around noon before VFR scattered cumulus arrives, then lifts further with another 100 degree afternoon. Expect the sea breeze, relatively copacetic, to arrive around 19Z in Brownsville, 20Z in Harlingen, and 22/23Z in McAllen...with the occasional gust to 20 knots in well-mixed air at McAllen just before sunset.

MARINE

Issued at 1204 PM CDT Sat Sep 19 2026

Generally favorable conditions will prevail with light to moderate southeasterly winds with seas around 2-3 ft and 6-7 second periods. Daily chances of showers and thunderstorms could lead to locally enhanced winds and seas.

PRELIMINARY POINT TEMPS/POPS

BRO WATCHES / WARNINGS / ADVISORIES

TX...None. GM...None.