textproduct: Brownsville/Rio Grande Valley

KEY MESSAGES

Updated at 544 PM CST Tue Nov 25 2025

-Dangerous surf and some tidal run-up at the beach Wednesday afternoon, impacting people here for the long holiday weekend

-Difficult boating conditions arrive Wednesday for Laguna Madre and the Gulf, continuing over the Gulf into Wednesday night

-Some welcome rain late tonight and Wednesday along a front that brings a short break through Friday from the record/near record heat of the past week

-Stronger front could arrive early Sunday with much cooler temperatures and dangerous surf/boating conditions returning

DISCUSSION

Issued at 1229 PM CST Tue Nov 25 2025

Tonight through Wednesday: The well-advertised front that will bring a change from early October heat to more 'normal' conditions headed into Thanksgiving is the main story early in the forecast. Along and especially behind the main boundary showers and perhaps an elevated thunderstorm are now expected, favoring the Rio Grande Plains/Brush Country/upper Valley between midnight and just after daybreak Wednesday, and the populated lower-mid Valley from pre-dawn through noon or so Wednesday. QPF forecast is somewhat tricky, as surface stability behind the front is countered a bit by decent diffluence aloft. High-Res (HREF) model probabilities for >0.5" are around 40% across the Rio Grande Plains/upper Valley overnight/early Wednesday, with similar values along the coast later on Wednesday. Bottom line? At most, very localized nuisance flooding where high rainfall rates fall over poor drainage areas. Otherwise, beneficial rain for most, and given the current moderate to extreme drought conditions, any little bit helps. High temperatures Wednesday will be dependent on both coverage and duration of rain. Persistent rain or rain with short breaks would only allow low to mid 70s for highs, but more breaks would be enough for upper 70s to around 80. The current blended forecast leans a bit warmer for the populated RGV (near 80) while 70-75 is common elsewhere. The probability for a larger error spread is greatest in the populated RGV if daytime rain is frequent vs. occasional. Either way, afternoon temperatures will be 10 to nearly 20 degrees lower Wednesday than on Tuesday.

Otherwise, the other issue arrives for those at or planning to head to South Padre to enjoy the still very warm (~80 degree) surf. For those there today, take advantage as strong northeast winds up to 25 mph with higher gusts arrive by or before noon, and dangerous surf with intense rip currents follow soon after. By late afternoon through early evening, tides may run up the beach given the direct swell direction onshore. Fortunately, predicted tides are in their low phase so notable coastal flooding is not anticipated...but enough of an energy surge could bring water to the dune line at narrow beaches from the north end of the City of SPI through the public beach access points. In short, vehicles should plan to be off the beach shortly after sunrise to ensure not getting surprised (and stuck) in any water later in the day.

Wednesday Night through Saturday Night: Any lingering light evening rain near the coast should end, with winds becoming light from the north. The overnight will be pleasantly cool, which is relative since forecast temperatures by daybreak Thanksgiving Day are where they should be (50 ranchlands, 55-60 Valley except near the coast). That said, temperatures may end up a bit higher than this depending on thickness of remaining clouds which would be an insulating blanket despite the light northerly flow. Aside from the clouds (especially for the Valley), Thanksgiving looks ideal for outdoor eating with temperatures at seasonal levels (mid to upper 70s), modest humidity, and light east winds as area is under subsidence aloft as the surface ridge eases into the Mississippi Valley.

Low to mid level southeast/south flow quickly returns Thursday night and especially Friday, aided by weak shear energy in broad westerly flow aloft. Latest GFS hinting at a warm-frontal type setup which could bring low chances (10-20%) of light rain/showers, favoring the ranchlands. The clouds will put somewhat of a lid on high temperatures..but even so, expect readings back to a degree or two above average (average for the 28th is mid 70s ranchlands, upper 70s Valley). Southeasterly flow picks up Friday night and Saturday, bringing a return to October-like conditions (temperature and humidity) with a soupy start and a warm, partly sunny afternoon). For the day, temperatures will be around 10 degrees above average for both minimum values (63 to 70) and maximum values (83 to 88). Another warm and humid night follows Saturday night into the wee hours Sunday, with light winds ahead of the next bigger front perhaps producing a period of fog.

Residual rip currents on South Padre for Thanksgiving will be a concern, before a one-day lull Friday. The stronger southeasterly flow arriving Friday night into Saturday will bring a pronounced south-north longshore and roughening/buliding surf as well.

Sunday through Tuesday: Models have come into agreement for a faster...and stronger...cold front as some of the coldest air of the season surges south through Texas. Shallow cold air often arrives in advance of when the global models think it might, so exact timing of the surge remains in question. Confidence has increased based on the recent GFS trend which now matches more closely with the deterministic ECMWF. NBM is likely lagging, so will get ahead of the situation and lower temperatures several degrees, especially across the ranchlands. That said, there is an increasing likelihood that afternoon temperatures Sunday could be up to 25 degrees cooler than on Saturday - with 10-25% probabilities (reasonable cold case) that readings could range from the low to mid 50s across most areas, except around 60 near the coast. We'll provide more details and perhaps a "sharp change" graphic on this tomorrow (Wednesday).

Should this occur, coastal conditions will also deteriorate with roughening/dangerous surf and perhaps some minor run-up by afternoon.

Monday and Tuesday will maintain the relative chill, along with clouds and pockets of light rain in southerly overrunning. Will lower temperatures a bit on these days as well (compared with the blends) to get on top of the situation. Bottom line? Potential is growing for the first multi-day window of much below average (daytime) temperatures that will make the start of December feel like...December.

AVIATION

(00Z TAFS) Issued at 544 PM CST Tue Nov 25 2025

Through 00z Thursday....VFR conditions are expected to prevail through this evening. However, over the next 6-9 hours, deteriorating weather conditions are expected to occur. Clouds will lower in elevation and increase in coverage with showers and thunderstorms developing after midnight tonight in response to an approaching frontal boundary.

Overnight tonight through the remainder of the flying conditions will primarily range between VFR and MVFR. Showers and storms are expected to develop and move into the TAF sites during the overnight hours sometime between 07z-12z. Any showers or storms that move over a TAF site will have the capabilities of reducing cigs/vsbys to IFR levels. The threat for widespread showers and storms will come to an end by noon on Wednesday. There could be some lingering showers during the afternoon hours with cloud coverage gradually improving through the rest of the day.

Winds will continue out of the southeast through this evening with speeds between 5-10 kts. Following the passage of a frontal boundary, winds will shift out of the northeast later tonight and persist through the remainder of the 00z period with speeds between 10-20 kts.

MARINE

Issued at 1229 PM CST Tue Nov 25 2025

Tonight through Wednesday Night: Light winds and generally slight seas will prevail through midnight before the surge of northeast flow arrives post-front/rapidly building pressure gradient soon after. Timing makes the issuance of the initial Small Craft Advisory difficult, as the strongest winds may arrive just before daybreak across the waters north of Port Mansfield and elsewhere at or just after daybreak. Model trends continue to increase winds into the 20- 25 knot range, and seas should easily reach 7, if not 8 feet, for a time between 9 AM and 6 PM Wednesday. Will add a "Small Craft Advisory Will Be Needed" headline to get ahead of the situation.

Laguna Madre winds should drop back below 15 knots soon after sunset Wednesday, but remain 15-20 knots and gusty across the Gulf well into the evening as seas may hold at or above 7 feet as well. Winds and seas should subside later at night to moderate levels by daybreak Thanksgiving.

Thursday through Saturday Night: Relatively benign conditions Thursday and Thursday night will begin deteriorating Friday, as east- southeast flow picks up in synoptic gradient that will be enough to overcome the weak marine layer to edge speeds toward Advisory levels by late afternoon. Seas will rise back toward 7 feet but probably hold up just short. That will not be the case Friday night into Saturday morning (at least) as gradient sharpens with low level southeast flow over 30 knots. Seas/wind waves will build over 7 feet making for very difficult conditions for small craft. Winds will be slow to subside Saturday as gradient slackens ahead of the next front, but seas may hold at or above 7 feet for much of the day. Conditions settle down to moderate levels...briefly...Saturday night before things get going again toward daybreak near Baffin Bay, post front.

Sunday and Sunday Night: Ranges of potential include winds of moderate Small Craft (20 to 25 knots) up to minimal Gale (frequent gusts of 35 knots) Sunday, dependent on the strength and intensity of the next front. More to follow as the event gets closer, but at minimum, Sunday will not be fit for small craft with gusts at or above 30 knots and seas building and churning back to at least 8 feet.

CLIMATE

Issued at 1229 PM CST Tue Nov 25 2025

The record/near record heat of the past week has pushed nearly all RGV locations into the top five warmest Novembers on record through the 24th. Those rankings may rise a bit higher after today (25th). With day/night averages only expected to drop close to the long-term normals, if not a touch above, Wednesday through Friday - and another 10 degree above average number for Saturday - we're locking in on another top-ten warmest finish for everyone when we count the numbers at the end of November. Sunday's now expected cool-down won't be enough to flip the script.

Here are the rankings, and departure from the top, for available locations (with minimal missing data) through the 24th:

Brownsville (since 1878): 76.3 degrees, #2, -0.8 degrees from #1 McAllen (since 1941): 76.9 degrees, #2, -1.1 degrees from #1 Harlingen (since 1912): 73.2 degrees, #6, -1.2 degrees from #1 Weslaco (since 1914): 74.6 degrees, #3, -1.3 degrees from #1 RGC (since 1897)*: 73.9 degrees, #4, -2.9 degrees from #1

PRELIMINARY POINT TEMPS/POPS

BROWNSVILLE 70 79 65 80 / 60 50 10 0 HARLINGEN 66 79 58 79 / 60 30 0 0 MCALLEN 69 79 60 80 / 60 40 0 0 RIO GRANDE CITY 65 76 54 78 / 70 40 0 0 SOUTH PADRE ISLAND 73 79 71 76 / 60 40 10 0 BAYVIEW/PORT ISABEL 68 79 65 78 / 60 40 0 0

BRO WATCHES/WARNINGS/ADVISORIES

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