textproduct: Brownsville/Rio Grande Valley

KEY MESSAGES

Updated at 1239 AM CDT Wed Sep 16 2026

- A Special Weather Statement (SPS) is in effect for Southern Hidalgo County as well as the coastal and inland portions of Kenedy, Willacy and Cameron counties (minus the barrier islands) on Wednesday for heat indices of 108-111 F, generally occurring within the hours of 11 AM to 6 PM.

- Near record-breaking heat and major to extreme risks of heat related illnesses (levels 3/4 and 4/4) on Wednesday improve to a moderate (level 2/4) to major risk by Thursday.

- Chances of rain increase to a low to medium (30-60%) chance and 30-50% chance on Thursday and Friday, respectively, minimize over the weekend and increase again next week.

- A low risk of life-threatening rip currents continues through Wednesday afternoon.

DISCUSSION

Issued at 1041 PM CDT Tue Sep 15 2026

The first focus of the forecast remains the brutal, near record triple digit heat expected again on Wednesday as ridging aloft and plentiful sunshine soars temperatures to around 6-8 degrees above average and enhancing moisture causes heat indices to max out around 105-111 F across the region, with extreme risks of heat- related illnesses expected across most of the RGV/Rio Grande Plains and a major heat risk elsewhere. Once again, a SPS is in effect on Wednesday across the lower and mid RGV, not including the barrier islands, for heat indices of 108-111 F, possibly briefly hotter.

The second focus is the anticipated unsettled weather brought in by a slight weather pattern change; a 1020-1030 mb surface high over the East Coast spills southwestward to the Gulf and transitions winds to easterly by Wednesday morning, gusting to near 20-25+ mph in the afternoon. This will aid in advecting inland deep Gulf moisture associated with a developing shortwave trough along the southern periphery of a retreating high pressure aloft, moistening PWAT values throughout Wednesday, peaking as high as 2.0-2.4+ in. Wednesday night into Friday before gradually drying throughout the later half of Friday; chances of rain along the daytime seabreeze boundary increase from a low (10-15%) chance across the lower and mid RGV on Wednesday to a region-wide low to medium (30-60%) and 20-50% chance on Thursday and Friday, respectively. Total forecast rainfall amounts Thursday into Friday have trended down, only expecting up to 0.20 of an inch. However, given such high moisture content, heavy downpours and some localized minor flooding are possible, particularly within any slower-moving or training of thunderstorms on Thursday and possibly Friday, which could quickly drop half an inch or more of rain.

Increased cloud coverage Thursday and Friday, followed by drier air funneling into the region as ridging resumes over the weekend, should help cool off temperatures to mostly the upper 90s by Thursday, which is still around 5 degrees above average, as well as improve heat risks from moderate to major on Thursday to mostly moderate Friday into Saturday. Yet, moisture and temperatures could rebound towards the end of the weekend, leading to moderate to major heat risks with additional SPSs for heat are possible by Sunday. Low to medium chances of rain return next week, potentially knocking down temperatures and improving heat risks again.

AVIATION

(06Z TAFS) Issued at 1239 AM CDT Wed Sep 16 2026

VFR will prevail at the aerodromes through the next 24 hours. Light winds for the remainder of the overnight hours will become moderate on Wednesday before diminishing around sunset. The next issuance of TAFs may need the mention of convection for at least one of the aerodromes if HRRR model guidance is to be believed.

MARINE

Issued at 1041 PM CDT Tue Sep 15 2026

Gentle to moderate southeasterly winds become northeasterly to easterly on Wednesday and easterly to southeasterly again over the weekend. Slight to moderate (2-4 ft) seas build to moderate (3-5 ft) Thursday before improving back to slight to moderate by Sunday. Low to medium (20-40%) chances of rain on Wednesday increase to a medium to likely (40-70%) chance on Thursday followed by a low to medium (20-50%) chance on Friday and Saturday. Chances of rain continue into next week as well.

PRELIMINARY POINT TEMPS/POPS

BROWNSVILLE 97 80 95 79 / 10 20 40 30 HARLINGEN 99 76 97 76 / 10 20 40 20 MCALLEN 103 80 99 79 / 10 10 60 20 RIO GRANDE CITY 103 78 99 78 / 10 0 50 20 SOUTH PADRE ISLAND 89 81 88 81 / 10 30 40 40 BAYVIEW/PORT ISABEL 95 78 94 78 / 10 20 40 30

BRO WATCHES/WARNINGS/ADVISORIES

None.