textproduct: Brownsville/Rio Grande Valley

KEY MESSAGES

Updated at 541 AM CDT Mon Aug 17 2026

- Conditions remain hot and mostly dry, except for a low (15-25%) chance of rain across the southern half of the lower and mid RGV on Monday.

- A Special Weather Statement (SPS) is possible for the inland portions of Cameron, Willacy and Kenedy counties on Monday for heat indices of 108-111 F.

- A mostly moderate risk of heat related illnesses (level 2/4) on Monday and Tuesday could escalate to a mostly major risk (level 3/4) by Thursday. Additional SPSs are likely and Heat Advisories are possible later in the week.

- The combination of low afternoon relative humidity coinciding with breezy to gusty conditions leads to fire weather concerns, especially Tuesday through Friday.

- A medium risk of life-threatening rip currents tonight becomes a low risk Morning morning, persisting through the afternoon hours.

DISCUSSION

Issued at 1018 PM CDT Sun Aug 16 2026

Increasing lower-level moisture and some divergence aloft, associated with an approaching weak mid-level trough, are expected to bring a low (15-25%) chance of rain to the southern portions of the lower and mid RGV tomorrow afternoon, highest across Southern Hidalgo. Brief heavy rain, occasional to frequent lightning and gusts of 30+ mph are possible. Increased cloud cover may help reduce the possibility of a SPS for heat indices of 108-111 F, though one may still be issued overnight tonight or Monday morning for Cameron, Willacy and Kenedy counties, depending on temperature and moisture trends. Highs on Monday are anticipated to reach into the upper 90s along/east US-281, while areas further west rise to the low/mid 100s, warmest over the Rio Grande Plains. A mainly moderate risk of heat-related illnesses (heat risk) is anticipated for Monday and again on Tuesday as sinking air behind the trough leads to much drier moisture content, with heat indices generally ranging between 100-110 F or a few degrees warmer. Drier air on Tuesday is likely to allow highs in the low/mid 100s to push eastward to the I-69 E corridor.

Otherwise, the previously discussed high pressure aloft regains control as it shifts westward from northern Texas to the Desert Southwest and 4 Corners region by the middle of the week before possibly re-emerging over the Southern Plains over this upcoming weekend, maintaining subsidence aloft and causing dry conditions to resume by Tuesday. An isolated shower or two along the daily seabreeze cannot be entirely ruled out later in the week. Additionally, a series of shortwaves running ahead of a developing trough over the Plains is progged to increase southeasterly winds, with gusts to 20-30+ mph possible by Tuesday, in turn spreading highs in the low/mid 100s to nearly all inland locations by Wednesday or Thursday. The resulting slight increase in moisture content is progged to deteriorate heat risks from moderate to major on Wednesday to mostly major, with pockets of extreme in urban areas, by Thursday. Additional SPSs are likely and heat advisories are possible toward the later parts of the week. Lastly, although conditions may be borderline, or beneath, Fire Danger Statement criteria, breezy conditions coinciding with lower afternoon minimum relative humidity values continue a risk of fire weather, particularly Tuesday into Friday, and caution is advised when handling outdoor flames.

A medium risk of life-threatening rip currents tonight becomes a low risk Monday morning, prevailing through the afternoon hours.

AVIATION

(12Z TAFS) Issued at 541 AM CDT Mon Aug 17 2026

VFR will generally prevail at the aerodromes through the next 24 hours. The only significant change to the previous issuance of TAFs is the inclusion of a TEMPO at MFE for convection this evening, with timing based on the HRRR model.

MARINE

Issued at 1018 PM CDT Sun Aug 16 2026

Gentle to moderate easterly to southerly winds transition to moderate to fresh easterly winds, with periods of Small Craft Exercise Caution, by Wednesday. Seas remain slight to moderate, building from 1-3 ft to 2-4 ft by Wednesday as well. Aside from a low to medium (20-40%) chance of rain from showers and thunderstorms during the morning and afternoon hours on Monday, conditions are expected to remain dry.

PRELIMINARY POINT TEMPS/POPS

BROWNSVILLE 96 80 97 80 / 10 0 0 0 HARLINGEN 98 76 100 76 / 10 0 0 0 MCALLEN 101 79 103 79 / 20 0 0 0 RIO GRANDE CITY 102 78 103 77 / 10 0 0 0 SOUTH PADRE ISLAND 89 81 89 81 / 10 0 0 0 BAYVIEW/PORT ISABEL 94 78 96 78 / 10 0 0 0

BRO WATCHES/WARNINGS/ADVISORIES

None.