textproduct: Brownsville/Rio Grande Valley

KEY MESSAGES

Updated at 1230 PM CDT Sat Aug 22 2026

- Hot and rain-free conditions will continue through late next week with "flash drought" situation worsening. - Moderate (level 2 of 4) to major risk (3 of 4) of heat-related impacts will worsen to major to extreme (level 4 of 4) by mid to late next week as overnight heat (upper 70s to 80s for most hours) accumulates while afternoon temperatures remain persistent between 100 (lower Valley) and 107-108 (Rio Grande Plains).

- Heat advisories may be needed along/east of US 281/IH-69C next week for afternoon apparent temperatures of 111 to 114. - The combination of low minimum relativity humidity values, dry fuels, very hot temperatures, and "pulse" gusts up to 25 mph could lead to the potential for rapid wildfire spread through the period.

DISCUSSION

Issued at 1230 PM CDT Sat Aug 22 2026

The broken record pattern of persistent heat, dryness, afternoon pulse wind gusts (25 mph or so) remains the story, as the location of the seasonally strong 500 mb ridge (heat dome) is locked just north of the classic "La Canicula" position (southern New Mexico/southwest Texas/northern Coahuila and Chihuahua) and extends across most of Texas/northeast Mexico into the western Gulf. Global models nudge the core of the ridge into the aforementioned La Canicula position early next week, as general late summer (weak) troughing sets up across the northeast/mid Atlantic region.

Toward the end of the period, the dome nudges west toward the southern New Mexico/Arizona border, but its eastward extent remains across most of Texas...which should keep any convection associated with the backside of the eastern U.S. trough mainly across the central and eastern Gulf, keeping our region rain-free. A reasonable worst-case could bring isolated showers/storms toward the outer coastal waters...but nothing more.

Sensible weather, therefore, is on repeat. Otherwise, expect to see more periods of east-west moving cirrus/cirrostratus each day, which may allow for more picturesque sunrises - but the high clouds will have no influence on forecast temperatures, which rise to between 100 (lower Valley-eastern Kenedy) to 105-107 (upper Valley/Brush Country/Rio Grande Plains), and continue with sultry 80s to lower 90s through midnight (warmest west), only falling to between 75 and 82 (rural to urban) each morning. Light to near calm winds and the noticeable lenghthening darkness will help bring the minimum temperatures down in the rural areas...but overall, temperatures will be around 3 degrees above late August averages - which have just slipped from their annual perch on the 21st.

As for future heat advisories (111 or higher for 2 or more hours)? Current forecasts bring the potential back for locations mainly along/east of IH-69C/US 281 by Tuesday/Wednesday through next Saturday. However, the positive feedback loop of heat and evaporation drying the ground with little to no wetting dew suggests afternoon RH (based on dewpoints) may remain low enough to keep apparent temperatures between 105-110 in all areas.

Bottom line? Stay cool as best you can - there is no relief for at least the next 10 days.

AVIATION

(18Z TAFS) Issued at 1230 PM CDT Sat Aug 22 2026

It's mainly a VFR forecast, with scattered to broken cirrus/cirrostratus the main cloud feature. Expect to see few- scattered mainly VFR cumulus, favoring Harlingen/Brownsville Sunday morning between 14-17Z but that should be it. Otherwise, for the past two mornings, McAllen/Edinburg area have featured a short (TEMPO) window of low MVFR stratocumulus, so will add a group to cover, mainly between 10 and 14Z (5-9 AM). As for winds, will continue to add gusts around 20 knots this afternoon/early evening before diminishing steadily, and remaining light through mid morning Sunday before a modest pickup.

MARINE

Issued at 1230 PM CDT Sat Aug 22 2026

Surface high pressure dominating the entire Gulf, conditions are favorable and will remain so through the period, with mainly light winds and slight seas with low swell periods and no impactful rain through Thursday night. The heat-generated gradient near the coastline and across Laguna Madre create a bit more wind (and chop), but conditions should remain at 15 knots or less, precluding even Small Craft Exercise Caution conditions.

FIRE WEATHER

Issued at 1230 PM CDT Sat Aug 22 2026

While we're likely to fall just short of Fire Danger conditions (i.e. 15-20+ 20 foot wind), we're on the razor's edge when considering pulse gusts. Unlike earlier this week, however, the gradient does slacken enough to keep even a reasonable worst-case gust factor to 25 mph along/east of IH-69C/US-281, and 20 mph to the west. But the combination of flash drought, the potential for afternoon RH to fall into the 15-25% range west of IH-69C/US 281 (and 25-35% east of there) as well as re-cured fuels based on visuals and the above-average evaporation rates are enough to keep the wildfire prevention message front and center.

Burn bans remain in effect for all but Kenedy County, and just a spark combined with even a pulse gust could quickly turn into a wildfire that could spread fairly rapidly. Since late July, there were two large wildfires with nearly 1400 acres burned in western Brooks - an area that missed out on two rain events not too far away (southwestern Brooks). The last truly beneficial rain over a decent-sized area was on August 2...and those benefits are long dried up.

Continue to promote wildfire safety and prevention until further notice.

CLIMATE

Issued at 1230 PM CDT Sat Aug 22 2026

How hot, August? Through the 21st, ranking in the top two or three all-time for most available stations. Rival years include 2023 (tops for several locations) and 2009 (tops for McAllen). 2023 remains the hottest meteorological summer (June-August) and astronomical summer (June 21 - September 21, in general)...but 2026 is hot on its heels. Given the expected temperatures to remain around 3 degrees above average through the end of August, several locations may tie or even push ahead of 2023's benchmark.

Here are the current stats for August, through the 21st:

Location (since) August (Rank) Record (year)

Brownsville (1878) 90.0 (2) 90.5 (2023) McAllen (1941) 91.5 (2) 92.3 (2009) Harlingen (1912) 88.6 (5) 90.3 (2023) McCook (1942) 89.3 (4) 90.1 (1998) Port Mansfield (1958) 86.8 (2) 87.3 (2023) Rio Grande City (1897)* 90.3 (3) 93.0 (1901)* Weslaco (1914) 89.5 (2) 90.4 (2023) Raymondville (1913) 89.7 (1) 2026

PRELIMINARY POINT TEMPS/POPS

BROWNSVILLE 79 99 80 99 / 0 0 0 0 HARLINGEN 75 102 76 102 / 0 0 0 10 MCALLEN 78 104 79 104 / 0 0 0 10 RIO GRANDE CITY 76 105 76 105 / 0 0 0 0 SOUTH PADRE ISLAND 80 90 81 90 / 0 0 0 0 BAYVIEW/PORT ISABEL 77 97 78 97 / 0 0 0 0

BRO WATCHES/WARNINGS/ADVISORIES

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