textproduct: Brownsville/Rio Grande Valley

KEY MESSAGES

Updated at 1236 AM CDT Thu Aug 6 2026

- Moderate to major heat risks (levels 2 and 3 of 4) on Thursday become minor (1 of 4) to moderate Friday through Sunday as clouds and low to medium (15-40%) afternoon chances of rain cool temperatures slightly.

- A Special Weather Statement (SPS) is likely across most of deep south Texas on Thursday for heat indices of at least 108-111 F and a heat advisory is possible for inland Kenedy and Willacy counties.

- Chances of rain diminish by the beginning of next week and temperatures warm again, deteriorating heat risks back to mainly major with pockets of extreme (level 4 of 4) from the early to middle part of next week as heat indices climb back to at least 108-111 F.

- A medium risk of life-threatening rip currents continues through Thursday afternoon.

DISCUSSION

Issued at 1051 PM CDT Wed Aug 5 2026

A 594+ dam high pressure aloft remains persistent over the 4 Corners and southeastern US throughout most of the next 7 days, gradually building and peaking around 597+ dam Friday through Saturday. This is expected to result in another scorching hot day across the region on Thursday (ahead of any potential afternoon clouds/rain) with widespread inland air temperatures soaring into the lower/mid 100s along/west of I-69 E, while inland/coastal areas further east peak into the upper 90s as well as mid 80s along the immediate Gulf coast. As has been the recurring pattern for this ongoing weather setup, a SPS is likely to be issued overnight tonight or Thursday morning for all inland and coastal portions of deep south Texas as Thursday afternoon heat indices are expected to climb to at least 108-111 F. A heat advisory remains possible, particularly for inland portions of Kenedy and Willacy counties, for apparent temperatures of 111-113 F.

Meanwhile, a series of shortwaves traversing the northern and eastern periphery of the high's ridge leads to a southwestward extension of mid/upper level troughing to the Southern Plains from the Midwest, lowering heights just a bit as well as building cloud coverage and moisture content, resulting in a daily chance of rain along the afternoon/early evening seabreeze boundary Thursday into Sunday. Guidance still remains a bit incohesive at this time, but there is a 15-20% chance of isolated showers and a few thunderstorms across the Northern Ranchlands on Thursday and the Lower/Middle RGV on Friday, where chances increase to a 20-30% on Saturday, followed by a low to medium (20-40%) chance along/east of US-281 on Sunday, highest along/east of I-69 E.

Yet, again, models continue to diverge a fair amount on overall coverage and deepness of convection, with brief periods of heavy rain, frequent lightning and some gusty winds not out of the question, especially over the weekend as pockets of PWAT values could exceed 2.0 in. Regardless, this is likely to gradually lower temperatures by a few degrees Friday into Sunday, with lower 100s mainly limited to the Rio Grande Plains and the Upper RGV as well as kick heat indices down to around 105-110 F across the region, with mostly moderate heat risks and pockets of minor.

Following, high pressure aloft begins to stretch across the Southern Plains to another building high pressure over the northeastern Gulf, re-enhancing subsidence aloft, diminishing cloud cover/rain chances and causing temperatures to rebound; widespread lower/mid 100s high temperatures and moderate to major heat risks return by Monday, gradually deteriorating to major, with pockets of extreme, by the middle of next week. Additional SPSs and/or heat advisories are likely as heat indices maximize around 108-111 F for most locations.

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

AVIATION

(06Z TAFS) Issued at 1236 AM CDT Thu Aug 6 2026

Light southeast winds with a few passing low to mid level clouds prevail across Deep South Texas early this morning. Southeast winds are expected to increase 15 to 20 kts by mid to late morning with some gusts around 25 kts in the afternoon. A brief period or two of MVFR ceilings could impact MFE through around 14Z. Otherwise, VFR conditions are forecast to continue for the next 24 hours.

MARINE

Issued at 1051 PM CDT Wed Aug 5 2026

Moderate to fresh southeasterly winds become mostly gentle to moderate on Friday and through the weekend before re-enhancing back to moderate to fresh by the beginning of next week. Chances of showers and thunderstorms increase from a low (15-20%) chance to as much as a low to medium (30-60%) chance Saturday and Sunday before gradually winding down to 10% or less by next Monday or Tuesday. Slight to moderate (2-4 ft) seas continue, with periods of Small Craft Exercise Caution conditions possible from time-to- time.

PRELIMINARY POINT TEMPS/POPS

BROWNSVILLE 97 80 96 79 / 10 0 20 0 HARLINGEN 100 76 97 75 / 10 0 20 0 MCALLEN 103 80 101 78 / 10 0 20 0 RIO GRANDE CITY 103 77 101 76 / 0 0 10 0 SOUTH PADRE ISLAND 89 81 88 80 / 10 0 10 0 BAYVIEW/PORT ISABEL 96 79 94 77 / 10 0 10 0

BRO WATCHES/WARNINGS/ADVISORIES

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