textproduct: Brownsville/Rio Grande Valley

KEY MESSAGES

Updated at 1233 AM CDT Fri Jun 19 2026

* An Extreme Heat Warning is in effect for all of Deep South Texas, excluding the island from Noon to 7 PM CDT Friday.

* A conditional risk for showers and thunderstorms exist Friday afternoon through Friday evening; best chances (20-40%) will be along and west of IH-69C/US-281.

* Another chance (30-40%) for showers and thunderstorms exist Saturday afternoon into Saturday evening.

* There is a Marginal Risk (Level 1 of 4) for excessive rainfall on Saturday.

* The heat and humidity continues Sunday through next week; additional heat headlines may be needed.

DISCUSSION

Issued at 1109 PM CDT Thu Jun 18 2026

The two main weather headlines through the forecast period or through next week will be 1) the continuation of very warm to hot and humid conditons and 2) a conditional risk for showers and thunderstorms developing Friday afternoon through Friday evening and another, better chance for showers and thunderstorms developing on Saturday.

We start off the forecast period through tonight, where we have a Special Weather Statement (SPS) for all of Deep South Texas to account for the high heat indices lingering through the night. Overnight low heat indices will struggle to make it out of the 90s tonight and at most will fall well into the 80s. These temperatures will provide little to no relief through tonight from the very hot temperatures experienced earlier today.

Another very hot day is expected on Friday. Another Extreme Heat Warning is in effect for all of Deep South Texas, excluding the island from Noon to 7 PM CDT Friday. The combination of high temperatures in the mid 90s to lower 100s and very humid conditions will result in dangerous heat indices ranging between 112-121F degrees.

While another hot day is expected on Friday, we are closely monitoring the potential for showers and thunderstorms developing Friday afternoon through Friday evening. A few forecast models have signaled the potential for showers and thunderstorms developing Friday afternoon/evening. The major wildcard will be whether or not the strong sfc based heating will be enough to offset convective inhibition or "capping" that will be in place, amongst other atmospheric dynamics. Currently, the best chances for any development will be along and west of IH-69C/US-281. There is a low-medium (20- 40%) chance for development, particularly Friday evening. The Storm Prediction Center (SPC) does have the western half of our CWA under a general risk for thunderstorms on Friday. Any storms that form will be efficient rainfall producers capable of producing heavy rainfall. We will continue to monitor trends and update accordingly. Otherwise, expect for a rain-free and hot day on Friday. Similar to tonight, little to no relief from the heat can be expected as overnight low heat indices will once again struggle to make it out of the 90s.

Saturday will feature a very warm and humid day, not as hit as prior days due to the increase in cloud cover and the increased chances for diurnal showers and thunderstorms. We maintain low-medium (30- 40%) chances for showers and thunderstorms Saturday afternoon into Saturday evening areawide. Again, due to the elevated atmospheric moisture content with precipitable water (PWAT) values ranging between 1.80-2.25 inches, any showers or storms will have the capabilities of producing heavy rainfall that could lead to isolated instances of flooding and ponding of roadways. The Storm Prediction Center (SPC) has all of Deep South Texas under a general risk for thunderstorms on Saturday. Meanwhile, the Weather Prediction Center (WPC) has the entire area under a Marginal (Level 1 of 4) Risk for Excessive Rainfall on Saturday. High temperatures on Saturday will be in the low to mid 90s. Heat indices will range between 105-112F degrees, which supports a widespread Moderate (Level 2 of 4) Heat Risk on Saturday. An SPS or a Heat Advisory may be needed for at least portions of the area on Saturday.

Sunday through next week, forecast models and ensembles continue to depict a broad and anomalously strong 591-597 dam heat ridge complex developing over the Southern U.S. including Deep South Texas. This will continue the hot and humid theme through next week with highs in the mid 90s to lower 100s and heat indices ranging between 100- 120F degrees promoting day-to-day Moderate (Level 2 of 4) to Major (Level 3 of 4) Heat Risk. Additional heat headlines may be needed as this season is getting off to a hot start.

AVIATION

(06Z TAFS) Issued at 1233 AM CDT Fri Jun 19 2026

Light to moderate southeast winds and MVFR ceilings prevail across Deep South Texas early this morning. A mix of VFR/MVFR conditions will likely continue overnight with full VFR conditions expected to return mid to late morning. Southeast winds between 8 to 14 kts overnight will increase and become breezy later this morning with some gusts around 25 kts in the afternoon. MVFR conditions may return late in the period.

MARINE

Issued at 1109 PM CDT Thu Jun 18 2026

A Small Craft Advisory remains in effect till 7 AM CDT Friday for the Laguna Madre and the Gulf Waters. Friday through next week, mainly adverse (Small Craft Exercise Caution) conditions will be in place.

PRELIMINARY POINT TEMPS/POPS

BROWNSVILLE 96 84 94 83 / 0 10 20 10 HARLINGEN 97 81 94 80 / 0 10 30 10 MCALLEN 99 83 95 82 / 0 20 40 10 RIO GRANDE CITY 101 80 95 79 / 20 40 40 30 SOUTH PADRE ISLAND 90 84 88 84 / 0 10 20 10 BAYVIEW/PORT ISABEL 95 83 91 82 / 0 10 20 10

BRO WATCHES/WARNINGS/ADVISORIES

TX...Extreme Heat Warning from noon today to 7 PM CDT this evening for TXZ248>255-351-353>355.

GM...None.