textproduct: Brownsville/Rio Grande Valley

KEY MESSAGES

Updated at 555 PM CDT Sat Sep 5 2026

- A Special Weather Statement (SPS) is in effect today across Southern Hidalgo County as well as the inland and coastal portions of Cameron, Willacy and Kenedy counties (not including the barrier islands) for heat indices of 108-111 F, generally occurring between 12 PM to 6 PM.

- Mostly major to extreme risks of heat-related illnesses (levels 3/4 and 4/4) prevail through the forecast as afternoon heat indices continue to soar to 106-110+ F.

- Near daily low, occasionally medium, chances of rain persist through most of the forecast.

DISCUSSION

Issued at 1151 AM CDT Sat Sep 5 2026

The main focus of the forecast continues to be the unyielding heat, with temperatures persistently rising to near 5-7 degrees above average through Tuesday; widespread lower 100s (around 100-104 F) are likely across most inland areas, warmest across the Rio Grande Plains and the Upper RGV, where temperatures could reach 105-107 F. Increased cloud cover towards the middle part of the week may help temperatures to ease off a few degrees before a warming trend follows into the weekend. In the meantime, a SPS is in effect today for southern Hidalgo County as well as the coastal/inland portions of Cameron, Willacy and Kenedy counties (excluding the barrier islands) for heat indices of 108-111 F, generally occurring within the hours of 12 PM to 6 PM. Widespread extreme risks of heat-related illnesses along/west of US-281 today are expected to become more limited to the Rio Grande Plains and the mid/upper RGV tomorrow through Tuesday though patches of extreme are still possible across the lower RGV and western portions of the Northern Ranchlands while major risks are expected elsewhere.

Simultaneously, a weak inverted trough aloft lingers over Deep South Texas into tomorrow, bringing a low (15-25%) chance of rain along the afternoon and early evening seabreeze boundary, highest across western portions of Starr and Zapata counties today, where above average moisture content (PWAT values exceeding 2.0 in.) and more favorable divergence aloft could further build chances of rain to as much as a medium (40%) chance into the later evening hours before diminishing overnight tonight. Some locations further west could receive up to 0.4 of an inch, perhaps a bit more. This same pattern is likely tomorrow, though afternoon seabreeze convection should be more focused along/east of US-281. Should note that there still remains a fair amount of disagreement between short term hi. res. models, but it appears at this time that convection could be isolated, scattered at most, though an isolated strong thunderstorm, or two, is possible, with winds potentially gusting to 30+ mph along with frequent lightning in a few locations.

Ridging briefly takes over late tomorrow night, reducing chances of rain to a low (15-20%) chance on Monday, before the next series of weak inverted shortwaves re-elevates chances of rain from a low (15-30%) chance on Tuesday to a low to medium (20-50%) chance on Wednesday, remaining the highest along/east US-281. Following, subsidence aloft and drier conditions return, decreasing chances of rain from a low (15-25%) chance on Thursday to around 10% or less, or near 15%, at most, into next weekend. Moderate (level 2/4) to major heat risks on Wednesday gradually deteriorate to a major to extreme risk by the weekend. Additional SPSs are possible as heat indices continue to range between 106-110+ F.

A low risk of rip currents continues through tomorrow afternoon.

AVIATION

(00Z TAFS) Issued at 555 PM CDT Sat Sep 5 2026

VFR conditions will prevail through the TAF period with southeasterly winds decreasing this evening. Chances of showers and thunderstorms increase Sunday afternoon, but confidence is low at this time if they will impact the aerodromes.

MARINE

Issued at 1151 AM CDT Sat Sep 5 2026

Gentle to moderate southeasterly winds and slight to moderate (1-3 ft) seas continue into next weekend. Some unsettled weather is anticipated Tuesday into Thursday, with chances of rain possibly maximizing around a low to medium (30-60%) chance on Wednesday, followed by daily low (15-30%) chances into next weekend. The bulk of showers and thunderstorms are likely to be limited to the offshore (20-60 nm) Gulf waters.

PRELIMINARY POINT TEMPS/POPS

BROWNSVILLE 81 98 80 98 / 0 20 0 10 HARLINGEN 76 101 76 101 / 0 30 10 20 MCALLEN 81 103 80 103 / 10 30 0 10 RIO GRANDE CITY 79 103 79 103 / 30 20 30 10 SOUTH PADRE ISLAND 82 90 82 90 / 0 10 0 10 BAYVIEW/PORT ISABEL 78 94 78 96 / 0 20 0 10

BRO WATCHES/WARNINGS/ADVISORIES

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