textproduct: Brownsville/Rio Grande Valley

KEY MESSAGES

Updated at 1239 AM CDT Tue May 5 2026

Key Messages:

* A Moderate Heat Risk (Level 2 of 4) on Tuesday increases to a Moderate to Major Heat Risk (Level 3 of 4) on Wednesday as afternoon heat indices (aka "real feel" temperatures) soar to 105-110 F and potentially a couple degrees higher on Wednesday.

* Small Craft Advisory is in effect for the Laguna Madre and Nearshore Gulf Waters (0-20 nm out) from 12 PM to 10 PM Tuesday.

* A moderate risk of rip currents continues through Tuesday afternoon.

* Cold front passes through or stalls nearby on Thursday, increasing chances of rain to as much as a medium (40-50%) chance Thursday night.

* Slightly cooler temperatures from increased cloud cover decrease Heat Risks from Minor (Level 1 of 4) to Moderate on Thursday to a Minor risk Friday into the beginning of next week.

DISCUSSION

Issued at 1036 PM CDT Mon May 4 2026

The highest forecast confidence for the next 7 days across Deep South Texas continues to be through midweek as a mid/upper level low pressure shifts eastward from California, pushing a high pressure aloft from central Mexico to the western Gulf. Meanwhile, a tightened surface pressure gradient results in breezy southeasterly winds along/east of US-281, where gusts up to 25-35 mph Tuesday afternoon and 20-30 mph on Wednesday afternoon are likely, enhancing warm air advection and moistening relative humidity (RH) values across the region. High temperatures in the low/mid 90s along/east of US-281 and mid/upper 90s further west on Tuesday increase to the upper 90s and lower 100s F on Wednesday as a dryline pushes into the Upper RGV Wednesday afternoon, bringing compressional heating from downsloping and drier air, especially further west. Factoring in RH, maximum afternoon heat indices rise from around 105-110 F, with a Moderate Heat Risk, on Tuesday to several degrees warmer, with a Moderate to Major Heat Risk, on Wednesday. An SPS may be needed for Wednesday, especially along/east of US-281, where apparent temperatures could surpass 110 F for a few hours.

The remainder of the forecast continues to feature more uncertainty in regards to expected rain chances, temperatures and degree convection intensity in association with an approaching cold front and mid-level disturbance(s). The following represents our latest thinking, which will become more clear/confident, thus subject to change, in the coming days. As the trough slowly moves east over the Southern Plains Wednesday night into Thursday morning, a surface high pressure building in its wake pushes a cold front into southern Texas, potentially passing through or stalling nearby Deep South Texas on Thursday. This gradually increases chances of rain throughout Thursday to as much as a medium (40-50%) chance Thursday night, followed by diminishing chances throughout Friday. Increasing cloud cover should bump temperatures down from the 80s/90s, with a Minor to Moderate Heat Risk, on Thursday to the 80s and a Minor Heat Risk on Friday into the beginning of next week. 90s return Saturday as clouds begin to clear and chances of rain decrease. Overnight lows in the 70s continue, though the Northern Ranchlands could dip into the upper 60s Thursday and Friday night.

This portion of the forecast, beginning Thursday, also could bring the possibility of strong to severe storms, perhaps even multiple rounds. Several of the latest deterministic GFS runs have inconsistently portrayed this potential on Thursday and Friday nights as well as next Monday as forcing and ascension aloft increase ahead of a shortwave and another potential disturbance in the beginning of next week. Again, there remains much uncertainty and probabilities of strong to severe convection are low to very low at this time.

A medium risk of rip currents continues through Tuesday afternoon.

AVIATION

(06Z TAFS) Issued at 1239 AM CDT Tue May 5 2026

Some low and high level clouds with southeast winds around 10 knots prevail across Deep South Texas early this morning. MVFR ceilings are expected to develop overnight as southeast winds around 10 knots continue. Southeast winds will become breezy mid to late morning with some gusts between 25 to 30 knots possible in the afternoon. VFR conditions are expected mid to late morning with MVFR returning this evening.

MARINE

Issued at 1036 PM CDT Mon May 4 2026

A tightening pressure gradient results in fresh to strong south- southeasterly winds, strong gusts, moderate (3-5 ft) waves and rough conditions on the bay on Tuesday; a Small Craft Advisory goes into effect for the Laguna Madre and Nearshore Gulf Waters (0-20 nm out) from 12 PM until 10 PM Tuesday. The gradient eases throughout the remainder of Tuesday night, reducing southeasterly winds to moderate to fresh on Wednesday and gentle to moderate by Thursday. A cold front stalls or passes through on Thursday, bringing moderate easterly or northeasterly winds and moderate seas into Saturday. Gentle to moderate southeasterly winds resume on Sunday. Chances of rain increase to as much as a low to medium (30-40%) chance Thursday night. Low chances linger into Friday. Small Craft Exercise Caution headlines are possible through at least Wednesday and Thursday.

PRELIMINARY POINT TEMPS/POPS

BROWNSVILLE 90 77 94 77 / 0 0 0 0 HARLINGEN 93 75 97 74 / 0 0 0 0 MCALLEN 96 79 101 79 / 0 0 0 10 RIO GRANDE CITY 99 75 101 77 / 0 0 0 10 SOUTH PADRE ISLAND 83 77 85 77 / 0 0 0 0 BAYVIEW/PORT ISABEL 88 76 93 75 / 0 0 0 0

BRO WATCHES/WARNINGS/ADVISORIES

TX...None. GM...Small Craft Advisory from noon today to 10 PM CDT this evening for GMZ130-132-135-150-155.