textproduct: Brownsville/Rio Grande Valley

KEY MESSAGES

Updated at 114 PM CDT Tue Aug 18 2026

- Hot, dry, and at times breezy conditions will continue through the week and into the weekend.

- Moderate (level 2 of 4) to major risk (3 of 4) of heat-related impacts through the weekend with peak afternoon heat indices generally between 105 to 112 degrees.

- There is increased potential for wildfire spread Wednesday into Thursday due to gusty conditions and drying fuels.

DISCUSSION

Issued at 114 PM CDT Tue Aug 18 2026

The dog days of summer are here as a La Canicula ridge takes hold across the Desert Southwest, northern Mexico into the western Gulf states. There is strong consensus among the GFS, ECMWF, and CMC ensemble guidance with an anomalously strong 594 Dm ridge draped over our region for the next two weeks. While the super El Nino has helped keep the tropical systems away from the Gulf Coast and Atlantic basin, we do need the rain and unfortunately, our drought situation will likely get worse before any meaningful chances for relief. Indeed, the 6-10 day CPC outlooks show a 60-70 percent probability of above normal temperatures and 40-50 percent probability of below normal rainfall for Deep South Texas. Every day is pretty much rinse and repeat until further notice. There might be an isolated shower or even a thunderstorm along the sea breeze boundary each afternoon, but the overall pattern tends to suppress rainfall and convection chances.

Daily high temperatures are expected to range from the the upper 90s to around 105 degrees, except near the coast. The combination of hot temperatures and elevated dewpoints in the 70s will support heat indices generally between 105 to 110 degrees each afternoon. Heat indices may briefly reach 111+ at a few locations in the afternoon, especially Thursday and Friday. Widespread Moderate (Level 2 of 4) to Major (Level 3 of 4) Heat Risk expected through late week into the weekend. Whether a Special Weather Statement or Heat Advisory is issued for your area, be sure to exercise caution if spending time outdoors and always look before you lock.

The hot, dry, and at times breezy conditions will support the potential increase of fire weather concerns Wednesday into Thursday. The current D1 (Moderate) to D2 (Severe) drought coverage looks to expand further with the upcoming U.S. Drought Monitor. With such dry antecedent conditions, evapotranspiration rates are extremely high. The daily evapotranspiration rates have ranged between 0.4 and 0.5 inches per day here at WFO Brownsville. Combined with a 24-hour wind run of 100 to 200 miles each day, this represents extreme, peak atmospheric water demand. In other words, we have a rather dire situation from a water resource management and agricultural standpoint with worsening drought and ongoing hot conditions. With how rapidly fuels are drying out, it is no surprise that the Texas A&M Forest Service is now forecasting high to very high fire danger for Wednesday due to a combination of 15-20 mph winds gusting 25+ mph at times and dry fuels based on 100hr and ERC percentiles.

AVIATION

(18Z TAFS) Issued at 114 PM CDT Tue Aug 18 2026

VFR will prevail at the aerodromes through the next 24 hours. Breezy winds with higher gusts up to 20 kt during the day time will be followed by lighter winds for the nighttime hours. Dry weather with only scattered cloud cover is also expected.

MARINE

Issued at 114 PM CDT Tue Aug 18 2026

Generally favorable marine conditions will prevail along the Lower Texas Coast through the period with light to moderate winds and low to moderate seas. Generally low to marginally moderate rip current risk is expected as wave period increase to the 5-6 seconds range with a persistent southerly to south-southeasterly swell and 2-3 ft waves. 15-20 kt winds over the Laguna Madre mid to late week could also lead to Small Craft Exercise Caution conditions. With SSTs in the low 80s and waters looking inviting with the ongoing hot weather, please exercise caution and be aware of rip current risk.

PRELIMINARY POINT TEMPS/POPS

BROWNSVILLE 80 97 82 98 / 0 0 0 0 HARLINGEN 76 101 78 102 / 0 0 0 0 MCALLEN 80 103 81 104 / 0 0 0 0 RIO GRANDE CITY 77 103 79 104 / 0 0 0 0 SOUTH PADRE ISLAND 81 90 82 90 / 0 0 0 0 BAYVIEW/PORT ISABEL 79 97 80 97 / 0 0 0 0

BRO WATCHES/WARNINGS/ADVISORIES

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