textproduct: Brownsville/Rio Grande Valley

KEY MESSAGES

Updated at 555 PM CDT Tue May 12 2026

Key Messages:

* Mainly sunny and dry conditions warm temperatures from the 80s/90s today and tomorrow to the mid/upper 90s later this week.

* Minor Heat Risks (Level 1 of 4) continue, deteriorating to a Moderate to Major Heat Risk (Levels 2 and 3 of 4) over the weekend and into next week as afternoon heat indices build to 105-110 F.

* Unsettled weather could return this weekend and/or the beginning of next week, but currently a low to medium (20-40%) chance at most.

* A moderate risk of rip currents continues through this afternoon, improving to a low risk this evening through tomorrow afternoon.

DISCUSSION

Issued at 1235 PM CDT Tue May 12 2026

Winds remain light through the middle of this week across Deep South Texas, gradually transitioning from northeasterly today to southeasterly by Thursday morning as a surface high pressure settles offshore the southern US Gulf Coast. High pressure aloft maintains dry and mainly sunny conditions into this weekend as well. Troughing and a series of surface low pressure systems traversing the Plains leads to lowering heights over the Sierra Madre later in the week, resulting in breezy conditions beginning Thursday, with onshore southeasterly winds likely gusting to 20-30+ mph each afternoon. This will enhance warm air advection, warming high temperatures from the upper 80s/low 90s today and tomorrow up to widespread 90s by Thursday, becoming mostly mid/upper 90s over the weekend. Building lower level moisture will also promote a warming trend in maximum apparent temperatures and heat risks, rising and escalating from the low/mid 90s with Minor Heat Risks through Friday up to Moderate to Major Heat Risk over the weekend and into the beginning of next week as indices soar to 105-110 F; SPSs or Heat Advisories are possible on Sunday and Monday, though too early to tell at this time. Meanwhile, a shortwave moves across the Desert Southwest and into the Plains over the weekend, which may bring a low chance (15- 30%) for the Rio Grande Plains from showers thunderstorms developing over the Sierra Madre. Yet, PoPs don't increase across the region until perhaps the beginning of next week in response to a longwave trough moving into the Southern Plains and enhancing forcing and ascension aloft, bringing a low to medium (20-40%) chance of rain. Overnight lows in the 60s tonight and tomorrow night also warm up, with temperatures possibly only cooling to the low 80s over the weekend and into next week.

A moderate risk of rip currents continues through this afternoon, improving to a low risk this evening through tomorrow afternoon.

AVIATION

(00Z TAFS) Issued at 555 PM CDT Tue May 12 2026

Through 00z Thursday....VFR conditions are expected to prevail through the 00z TAF cycle. There could be a brief period of MVFR mist/low stratus early Wednesday morning due to the combination of calm winds and elevated levels of low level moisture.

East-northeast winds 5-10 kts this evening will trend towards light and variable to calm tonight. Light and variable to calm winds Wednesday morning will pick up out of the east-northeast with speeds between 5-10 kts mid morning to early afternoon.

MARINE

Issued at 1235 PM CDT Tue May 12 2026

Gentle to moderate northeasterly winds gradually become southeasterly by Thursday morning along with slight to moderate (1-3 ft) seas. Small Craft Exercise Caution conditions return Thursday and into the beginning of next week as the pressure gradient tightens, resulting in moderate to fresh southeasterly winds and moderate (3-5 ft) seas, occasionally higher. Chances of rain gradually increase to a low to medium (20-40%) chance in the beginning of next week.

PRELIMINARY POINT TEMPS/POPS

BROWNSVILLE 68 89 69 90 / 0 0 0 0 HARLINGEN 64 89 63 91 / 0 0 0 0 MCALLEN 68 91 68 94 / 0 0 0 0 RIO GRANDE CITY 67 91 67 93 / 0 0 0 0 SOUTH PADRE ISLAND 74 81 75 83 / 0 0 0 0 BAYVIEW/PORT ISABEL 68 85 69 87 / 0 0 0 0

BRO WATCHES/WARNINGS/ADVISORIES

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