textproduct: Brownsville/Rio Grande Valley

KEY MESSAGES

Updated at 559 PM CDT Fri Jun 19 2026

* An Extreme Heat Warning is in effect for all of Deep South Texas, excluding the island until 7 PM this evening.

* Isolated to scattered showers and thunderstorms are possible through Saturday night. Rain chances range from 20-40% along and west of I-69C this evening and 20-40% across the area Saturday. Isolated strong to severe thunderstorms are possible today.

* Heat will continue to be a concern over the weekend with Heat Advisories likely Saturday and possible Sunday.

DISCUSSION

Issued at 1246 PM CDT Fri Jun 19 2026

A moist air mass is forecast to remain in place through Saturday, with PWAT values generally ranging from 2 to 2.5 inches and dewpoints in the upper 70s to low 80s across the area. Combined with afternoon temperatures climbing to the upper 90s to low 100s this afternoon, and low to mid 90s Saturday, heat will continue to be a concern with heat index values ranging from 115-118 this afternoon and 105-112 Saturday. An Extreme Heat Warning is in effect until 7 PM today, and a Heat Advisory will likely be needed Saturday afternoon.

In addition to the heat, a shortwave trough moving across Texas, and a frontal boundary spanning across Central Texas will likely increase forcing across the area, which may be able to tap into the abundant moisture to produce isolated to scattered showers and thunderstorms today through Saturday. Rain chances this afternoon are primarily confined to western portions of the CWA, where convection developing along the Sierra Madre may cross the Rio Grande before weakening or dissipating. Rain chances are forecast to spread across the area tonight, though thunderstorm activity will be less likely overnight, an isolated thunderstorm cant be ruled out.

Ample instability and wind shear this afternoon and evening could allow for some strong to severe thunderstorms to develop and move into western portions of the CWA. The Storm Prediction Center has Zapata, and portions of Jim Hogg and Starr counties under a Marginal Risk for Severe Weather (level 1 of 5) today. Additionally, given the abundant moisture, heavy rain will be possible with any shower or thunderstorm that develops, and isolated flash flooding will be possible. The Weather Prediction Center has Zapata, and portions of Jim Hogg and Starr counties under a Marginal Risk for Excessive Rainfall (level 1 of 4) today and tonight and a Marginal Risk for the entire CWA Saturday.

Rain chances are forecast to diminish Sunday, with generally rain free conditions forecast through the remainder of the period. High temperatures are forecast to return to the mid to upper 90s Sunday through the end of the period. However, humidity values are forecast to gradually decrease next week, allowing Heat Index values to fall to generally remain below 111 degrees, limiting the need for additional Heat Advisories.

AVIATION

(00Z TAFS) Issued at 559 PM CDT Fri Jun 19 2026

Somewhat breezy southeasterly winds this evening (12-15 knots, gusting to 19-23 knots) are expected to persist through much of tonight, though could lower to around 10 knots in the pre-dawn or morning hours. VFR conditions are expected to become MVFR overnight, with ceilings possibly as low as 1,200-1,500 ft late tonight or early Saturday morning. MVFR conditions gradually become broken or scattered VFR by the afternoon hours, with PROB30s included for KMFE and KHRL for the late afternoon and early evening hours due to the low to medium (20-40%) chance of isolated to scattered showers and thunderstorms. Southeasterly winds return to similar speeds as today by the afternoon hours as well.

MARINE

Issued at 1246 PM CDT Fri Jun 19 2026

Adverse marine conditions are forecast to continue through early next week, with winds generally ranging from 15 to 20 knots and seas between 4-6 feet. Conditions look to improve Tuesday with generally favorable marine conditions forecast through the remainder of the period.

PRELIMINARY POINT TEMPS/POPS

BROWNSVILLE 84 94 83 94 / 10 20 20 0 HARLINGEN 81 94 80 95 / 10 30 20 0 MCALLEN 82 95 82 96 / 20 30 20 0 RIO GRANDE CITY 80 95 79 99 / 30 40 30 0 SOUTH PADRE ISLAND 84 89 84 89 / 10 10 20 0 BAYVIEW/PORT ISABEL 83 92 82 93 / 10 20 20 0

BRO WATCHES/WARNINGS/ADVISORIES

TX...Extreme Heat Warning until 7 PM CDT this evening for TXZ248>255- 351-353>355.

GM...None.