textproduct: Brownsville/Rio Grande Valley

KEY MESSAGES

Updated at 1257 PM CDT Mon Jul 13 2026

- Despite some exceptions and uncertainty in rain chances into the middle of this week and again this weekend, there is a lean towards low (15-20%) chances of rain continuing into early this evening followed by mainly dry conditions (<10% chances of rain) by tonight and beyond.

- Afternoon heat indices drop from around 105-110 F today to near 100-105 F by tomorrow as the bulk of deep, tropical moisture moves out today. A progressively drier trend results in moderate heat risks (level 2 of 4) becoming a minor (level 1 of 4) to moderate heat risk over the weekend into early next week.

- The Weather Prediction Center (WPC) highlights extreme northwestern Zapata County within a Marginal Risk of Excessive Rainfall (level 1 of 4) with the possibility of isolated flash flooding Wednesday through Wednesday night.

- Temperatures may rise a few degrees above average this weekend, though uncertainty remains.

- A medium risk of life threatening rip currents continues through tomorrow afternoon.

DISCUSSION

Issued at 1257 PM CDT Mon Jul 13 2026

The latest satellite and radar imagery (12:46 PM) reveals streamer clouds with isolated to scattered passing showers along/east of US-281 as the final push of residual, deeper Gulf moisture propagates a low (15-20%) chance of rain westward along the seabreeze boundary into early this evening. Due to the very moist airmass still in place, rain could be briefly heavy. A thunderstorm or two is not out of the question as well. Following, aside from a daily potential for an isolated afternoon shower or two, a weak upper level high pressure stretching over the Gulf and into deep south Texas *could* keep mostly dry conditions for the remainder of the forecast. A drying trend in moisture content is anticipated as well, with afternoon heat indices reducing from near 105-110 F today to around 100-105 F by tomorrow. This should maintain a moderate heat risk though the Northern Ranchlands could improve to a minor to moderate heat risk over the weekend.

However, there still remains some uncertainty as to how far south forcing associated with a weak trough aloft, arriving over central and southern Texas tonight, extends as a few of the latest global and hi. res. runs indicate the possibility of some lighter showers making their way into the Northern Ranchlands and Rio Grande Plains into the middle of this week. There is also the potential for some heavier rain on Wednesday as building high pressure over the eastern US shifts the trough to western Texas; WPC includes extreme northwestern Zapata County within a Marginal Risk of Excessive Rainfall (level 1 of 4), leading to possible isolated flash flooding, Wednesday through Wednesday night.

Additionally, there is some discrepancy amongst long range guidance, supporting either an enhanced high pressure or weak low pressure within the middle to upper layers of the atmosphere this weekend, resulting in either sunnier skies with warmer and drier conditions or cloudier skies and slightly cooler temperatures from unsettled weather, respectively. At this time, we are leaning towards the drier and warmer solution, but this is subject to change as confidence increases over the next several days.

Despite these uncertainties, we generally anticipate near average temperatures for most of the forecast. Should stronger high pressure dominate this weekend, we could rise a bit above average, with mostly upper 90s along/east of US-281/I-69 C and a more expansive area of lower 100s further west.

A medium risk of life-threatening rip currents continues through tomorrow afternoon.

AVIATION

(18Z TAFS) Issued at 1257 PM CDT Mon Jul 13 2026

Southeasterly winds of around 10-15 knots, gusting to 20-25 knots, are likely to continue into the late afternoon hours, gradually dropping through sunset to gentle into the early nighttime hours tonight. Scattered to broken VFR conditions are likely to persist, though low chances of spotty light rain showers could occur from time to time through this afternoon at KBRO and KHRL, but probabilities are too low to include within the TAF. Amendments are still possible. Otherwise, drier conditions resume by this evening. Southeasterly winds return to similar strength as today by early tomorrow afternoon.

MARINE

Issued at 1257 PM CDT Mon Jul 13 2026

Moderate to fresh southeasterly winds and moderate (3-5 ft) seas continue through the next 7 days. Just like this afternoon, Small Craft Exercise Caution headlines are likely from time-to-time for the Laguna Madre and possibly the nearshore Gulf waters (0-20 nm out), especially during the afternoon and evening hours. Other than a low (15-30%) chance of rain today and Wednesday, mainly dry conditions prevail with a less than 10% chance of rain. However, due to uncertainties in the forecast, this could change.

PRELIMINARY POINT TEMPS/POPS

BROWNSVILLE 80 94 81 94 / 10 0 0 0 HARLINGEN 77 96 79 95 / 10 0 0 0 MCALLEN 79 99 81 98 / 10 0 0 0 RIO GRANDE CITY 77 100 79 98 / 10 0 0 0 SOUTH PADRE ISLAND 81 88 82 88 / 10 0 0 0 BAYVIEW/PORT ISABEL 79 92 80 92 / 10 0 0 0

BRO WATCHES/WARNINGS/ADVISORIES

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