textproduct: Brownsville/Rio Grande Valley

KEY MESSAGES

Updated at 1219 PM CDT Thu Jun 18 2026

* An Extreme Heat Warning is in effect today until 8 PM CDT. Heat indices exceeding 120 degrees are expected throughout Deep South Texas this afternoon and early evening.

* Little relief from the heat is expected tonight (heat indices are expected to remain above 90). An Extreme Heat Watch is in effect tomorrow from 11 AM to 8 PM CDT.

* There is a low to moderate (20 to 40%) chance of showers and thunderstorms in the Western Ranchlands Friday and Saturday night. Low to moderate chances extend to all of Deep South Texas during the day on Saturday.

* A Moderate Risk of Rip Currents continues for area beaches through tomorrow afternoon.

* A Small Craft Advisory is in effect this afternoon through tomorrow morning.

DISCUSSION

Issued at 1219 PM CDT Thu Jun 18 2026

An Extreme Heat Warning is in effect for all of Deep South Texas (excepting the barrier islands) this afternoon and evening until 8 PM CDT. Heat indices of 120 or higher are possible for the entire region today (excepting the islands), which are the highest heat indices we have had since 2024. In addition, an Extreme Heat Watch is also in effect for Friday as well, with little relief from the heat expected overnight. The heat index is likely to stay above 90 degrees overnight, and climb back up between 115 and 120 degrees tomorrow. Tomorrow's Extreme Heat Watch may need to be upgraded to a warning later this evening.

Moderate to Major Heat Risk concern will continue into the weekend, and while heat indices will not be as high as today and tomorrow, the heat index in some places could exceed 110 degrees in some areas (especially in the Lower Rio Grande Valley) Saturday through Monday. Additional Heat Advisories may be needed over the weekend. Conditions should slightly improve on Tuesday, but the heat index will still reach the triple digits. Actual temperatures will lower from the upper 90s/lower 100s this weekend to the mid-to-upper 90s by mid-week. However, the heat index is more representative of how hot it is going to feel outside over the next several days.

Conditions should be overall rain-free throughout the next week, but a weak mid-level disturbance is expected to enhance the potential for Sierra Madre convection to form in Mexico and move eastward into our CWA starting Friday evening. The Western Ranchland Counties could see some showers and thunderstorms (20 to 40% likelihood) Friday night. These same low to moderate chances then spread across Deep South Texas on Saturday before the Western Ranchlands could see another round of Sierra Madre showers and thunderstorms Saturday night as well. Flooding shouldn't be too much of a concern for most places, but an isolated flash flood cannot be ruled out if an area that already received heavy rainfall earlier this week also receives localized heavy rainfall this weekend. Therefore, the Weather Prediction Center has included Deep South Texas in a Marginal (level 1 of 4) Risk of excessive rainfall for Saturday.

A moderate risk of life threatening rip currents remains in place through tomorrow.

AVIATION

(18Z TAFS) Issued at 1219 PM CDT Thu Jun 18 2026

VFR conditions with clear skies and southeasterly winds are expected at all airports through this evening. Overnight, clouds will develop between 02-04z and ceilings should lower to MVFR for HRL and BRO. MFE should remain at VFR but still develop some overnight clouds.

MARINE

Issued at 1219 PM CDT Thu Jun 18 2026

A Small Craft Advisory is in effect for the Bay and Nearshore Waters this afternoon through tomorrow morning due to elevated wind gusts and seas. The Offshore Waters have a Small Craft Advisory in effect until 12z tomorrow morning starting at 00z. Intermittent periods of SCEC are possible this weekend through early next week until conditions improve to more favorable by midweek.

PRELIMINARY POINT TEMPS/POPS

BROWNSVILLE 84 96 84 94 / 0 0 10 20 HARLINGEN 81 97 81 94 / 0 0 10 20 MCALLEN 83 98 83 95 / 0 10 20 40 RIO GRANDE CITY 81 100 80 95 / 0 20 30 30 SOUTH PADRE ISLAND 85 90 85 89 / 0 0 10 10 BAYVIEW/PORT ISABEL 83 94 83 92 / 0 0 10 20

BRO WATCHES/WARNINGS/ADVISORIES

TX...Extreme Heat Warning until 8 PM CDT this evening for TXZ248>255- 351-353>355.

Extreme Heat Watch from Friday morning through Friday evening for TXZ248>255-351-353>355.

GM...Small Craft Advisory until 7 AM CDT Friday for GMZ130-132-135- 150-155.

Small Craft Advisory from 7 PM this evening to 7 AM CDT Friday for GMZ170-175.