textproduct: Brownsville/Rio Grande Valley

KEY MESSAGES

Updated at 1220 AM CDT Sun Sep 13 2026

- A Special Weather Statement (SPS) is in effect on Sunday across all of deep south Texas, with the exception of the barrier islands, for heat indices of 108-111 F.

- Widespread extreme risks of heat-related illnesses (level 4/4) prevail through Monday, gradually improving from a major (level 3/4) and extreme risk on Tuesday and Wednesday to a mainly moderate (level 2/4) risk by Thursday.

- Fire weather concerns prevail, most concerning Sunday into Tuesday.

- Aside from a low (15-20%) of rain on Sunday, hot and dry conditions persist through Tuesday before daily afternoon low (15-30%) chances of rain return by midweek, increasing to as much as a low to medium (20-40%) chance on Thursday and Friday.

- A medium risk of rip currents tonight becomes a low-risk by Sunday morning.

DISCUSSION

Issued at 1039 PM CDT Sat Sep 12 2026

A weak mid/upper level inverted trough riding along the southwestern periphery of a high pressure aloft could deliver a low (15-20%) chance of brief and isolated rain showers, and perhaps a thunderstorm or two, along the afternoon seabreeze to the lower RGV on Sunday and again on Monday morning (15% chance). Due to the associated elevated moisture content (PWAT up to as high as 1.9-2.0+ in.) and otherwise plentiful sunshine with well-above average temperatures and dry conditions, an SPS is in effect for all of deep south Texas, minus the barrier islands, on Sunday for heat indices warming to around 108-111 F, generally within the hours of 12 PM to 6 PM, though a few areas could briefly surpass 111 F. Widespread extreme risks of of heat-related illnesses and SPSs for heat are likely on Monday as well.

As the high pressure aloft shifts eastward and builds to 597+ dam over the Deep South by Tuesday, drier air and subsidence aloft reduce chances of rain to 10% or less on Tuesday and result in a major to extreme heat risk into Wednesday, as highs continue soaring well above average, into the low/mid 100s across most inland areas, though topping out in the upper 100s (around 107+ F) over the Rio Grande Plains. Following, a considerable break in the heat is possible by Thursday as an area of deep moisture (PWAT of 2.0- 2.0+ in.) over the Gulf seeps westward into our CWA via easterly winds, increasing chances of rain from a low (15-20%) chance on Wednesday to a region-wide low to medium (20-40%) chance on Thursday and Friday, highest along/east of US-281, with additional low chances over the weekend. Increased clouds should help reduce high temperatures to mainly the upper 90s, though lower 100s are possible over the Rio Grande Plains, as well as reduce heat risks to a mainly moderate risk by Thursday. However, additional SPSs are possible through at least Wednesday.

Additionally, although fire weather conditions are expected to be borderline to below Fire Danger Statement criteria, fire weather concerns persist through the next 7 days, with the greatest risks each afternoon Sunday through Tuesday as breezy southeasterly winds, around 15-20 mph and gusting to 25-30+ mph, coincide with minimizing relative humidity values.

A medium risk of life-threatening rip current tonight becomes a low risk Sunday morning through the afternoon hours.

AVIATION

(06Z TAFS) Issued at 1220 AM CDT Sun Sep 13 2026

VFR conditions are expected to generally prevail through the TAF period with a southeast breeze through the afternoon. There is a low (less than 20 percent) chance of a thunderstorm along the sea breeze late morning into early afternoon, with very low confidence in any CB within RGV aerodromes at this time.

MARINE

Issued at 1039 PM CDT Sat Sep 12 2026

Moderate to fresh southeasterly winds become gentle to moderate and easterly by midweek while slight to moderate (2-4 ft) seas prevail. Periods of Small Craft Exercise Caution headlines are possible through the beginning of the week. Chances of rain gradually wane from a low to medium (20-40%) chance on Sunday down to 10% or less by Tuesday before increasing again from a low to medium (20-40%) chance on Wednesday to as much as a medium (40-60%) on Thursday and Friday, followed by lower chances over the weekend.

PRELIMINARY POINT TEMPS/POPS

BROWNSVILLE 81 97 81 98 / 10 10 0 0 HARLINGEN 78 101 77 102 / 10 10 0 0 MCALLEN 81 103 81 103 / 0 0 0 0 RIO GRANDE CITY 80 104 79 105 / 0 0 0 0 SOUTH PADRE ISLAND 82 90 83 90 / 10 10 0 0 BAYVIEW/PORT ISABEL 79 96 79 96 / 10 10 0 0

BRO WATCHES/WARNINGS/ADVISORIES

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