textproduct: Brownsville/Rio Grande Valley

KEY MESSAGES

Updated at 1221 AM CDT Mon Jun 1 2026

* Seasonably warm temperatures (low/mid 90s) continue into Monday and Tuesday, with a mostly moderate heat risk (level 2 of 4) on Monday becoming a mainly minor risk (level 1 of 4) by Tuesday as clouds build.

* A low (15-30%) chance of rain on Monday and Tuesday increases to a low to medium (as much as 20-50%) chance Wednesday through Friday before gradually lower next weekend.

* Although uncertainty remains, WPC includes a Marginal Risk (level 1 of 4) of isolated flash flooding from excessive and heavy rainfall for northwestern Zapata County on Thursday.

* A medium risk of rip currents continues through Monday afternoon and is likely to become a high risk throughout the week.

DISCUSSION

Issued at 1028 PM CDT Sun May 31 2026

Although somewhat weak, a high pressure aloft maintains a stronger hold through the next 24-48 hours, bringing mainly dry conditions across most of deep south Texas through Monday. Meanwhile, lower- to-mid level (surface to 700 mb) moisture increases as southeasterly and easterly winds over the Gulf advect the tail end of a deep and tropical moisture-rich plume northwestward and westward into our region. By Monday afternoon, PWATs could meet and exceed both the 75th and 90th percentile PWAT sounding climatology of roughly 1.7 and 1.9 in., respectively, with the higher end residing along/east of US-281, persisting over the next 7 days. All of this considered, another seasonably hot forecast is anticipated into Tuesday, with highs reaching into the low/mid 90s. More abundant sunshine and very high relative humidity on Monday are likely to soar maximum afternoon heat indices to around 100-105 F, thus bringing a mainly moderate heat risk to the CWA. There is a low (15-30%) chance of rain, expanding in coverage and further north from a few spotty showers across the Lower and Middle RGV on Monday afternoon to isolated to scattered showers and a few thunderstorms all along/east US-281 on Tuesday afternoon.

Heading towards the middle part of the week, cloud coverage builds further as a mid/upper level trough slowly pushes eastward across northern Mexico and steadily lowers 500 mb heights. This, in combination with easterly winds over the northern Gulf, is anticpated to result in a daily low to medium (20 to 40% or 50%) chance of rain by Wednesday, continuing to peak in coverage and activity during the afternoon hours along the seabreeze boundary, followed by a low (15-30%) chance overnight. PoPs look to be the greatest along/east of US-281, where the higher moisture content remains. An isolated strong thunderstorm or two is not out of the question due to such high instability and moisture content in addition to a slight increase in forcing for ascension aloft. Therefore, although most areas are only expected to receive around 0.05-0.10 of an inch of rain in each round, slow storm movement and/or deeper convection could lead to higher amounts, perhaps to an inch or more. Nonetheless, increased cloud cover should keep high temperatures in the upper 80s/lower 90s Wednesday into Friday, while apparent temperatures peak around 97-103 F, resulting in mainly minor heat risks, though portions of the RGV still continue a moderate risk.

Later in the week, weak mid-level impulses embedded within troughing arriving over Texas could develop stronger thunderstorms and heavier rain over south Texas; WPC has introduced a Marginal Risk (level 1 of 4) of isolated flash flooding from excessive and heavy rainfall for the northwestern corner of Zapata County on Thursday. Additionally, gradual development of an area of surface low pressure over the Gulf may occur. Therefore, additional changes to the forecast are likely over the coming days as details become clearer. Otherwise, high pressure aloft regains control next weekend, causing rain chances to gradually diminish and heat risks to escalate as temperatures and heat indices climb.

A medium risk of rip currents continues through Monday afternoon and is expected to become a high risk throughout the upcoming week as wave heights build and periods lengthen.

AVIATION

(06Z TAFS) Issued at 1221 AM CDT Mon Jun 1 2026

Generally VFR will prevail at the aerodromes through the next 24 hours, with clear to partly cloudy skies and light to moderate winds.

MARINE

Issued at 1028 PM CDT Sun May 31 2026

Gentle to moderate easterly to southeasterly winds become mostly moderate, fresh at times, later in the week. Slight to moderate (2-4 feet) seas build to moderate (3-5 feet) seas on Tuesday, possibly elevating a bit more later into the week and next weekend in response to a potential surface low pressure system over the Gulf. Rounds of showers and thunderstorms are expected to bring at least a daily low (15-30%) chance of rain beginning Monday and increasing to as much as a low to medium (20-50%) chance on Tuesday.

PRELIMINARY POINT TEMPS/POPS

BROWNSVILLE 92 79 91 78 / 10 10 30 10 HARLINGEN 92 76 91 74 / 20 10 30 10 MCALLEN 96 78 94 77 / 10 0 20 0 RIO GRANDE CITY 96 77 95 76 / 0 0 10 10 SOUTH PADRE ISLAND 86 81 85 81 / 10 10 20 30 BAYVIEW/PORT ISABEL 89 78 89 78 / 10 10 20 10

BRO WATCHES/WARNINGS/ADVISORIES

None.