textproduct: Brownsville/Rio Grande Valley

KEY MESSAGES

Updated at 456 PM CST Sun Jan 4 2026

* Warmer than normal temperatures, rain-free, and at times breezy conditions are expected to persist through through next week.

* Patchy mist, fog, and/or low stratus is possible tonight across the region.

* Our next cold front is set to arrive in the Friday-Saturday timeframe.

* Breezy southerly winds are expected to develop ahead of the cold front Wednesday-Thursday.

DISCUSSION

Issued at 1242 PM CST Sun Jan 4 2026

Low amplitude, zonal to semi-zonal (west-southwest flow aloft) 500 mb regime with plenty of subsidence will continue to foster warmer than normal temperatures, mostly to partly sunny skies, and at times breezy conditions with patchy mist/fog possible during the night across Deep South Texas and the Rio Grande Valley through the first full week of January 2026.

Despite some weak cool air advection (CAA) following the passage of a weak cool front, strong sfc based differential heating courtesy of an anomalously strong 585-588 mb ridge axis overhead will allow for daytime highs to reach levels that are well above normal for this time of year with readings on track to range from the upper 70s to lower 80s across Deep South Texas and the Rio Grande Valley. Throughout the day today, winds will also begin to shift from the east-northeast to more out of the east-southeast.

For tonight, a southeasterly wind component will take over, which will begin the process of increased moisture and warm air advection (WAA). If there are enough break in the clouds, there could be enough radiational cooling applied coupled with light winds and some low level moisture to support the development of some mist, fog, or low stratus. Confidence is higher for mist and low stratus as opposed to fog for tonight according to BUFKIT soundings and NBM probabilities. As of this update, there is a low-medium (30-50%) chance for mist, fog, and/or low stratus to develop tonight along the Rio Grande Valley with slightly higher (40-60%) chances for mist, fog, and/or low stratus developing across the Rio Grande Plains and Northern Ranchlands. Otherwise, expect for another quiet night with warmer than normal temperatures. Overnight lows are progged to be in the upper 50s over the Northern Ranchlands and the lower 60s along the RGV, some 10F degrees above normal.

As highlighted above, an unseasonably warm and rain-free regime will prevail through the first full week of January 2026. Through Thursday, high temperatures are progged to be in the mid to upper 80s across Deep South Texas and the Rio Grande Valley. Meanwhile, overnight lows through Thursday night are expected to mainly be in the 60s.

Forecast models/ensembles continue to advertise a cold front emanating from the Pacific Northwest sweeping through Deep South Texas in the Friday-Saturday timeframe. Given that this cold front will be moisture starved, dry conditions by and large expected to persist through the upcoming weekend. As a 1020-1030 mb sfc high or Canadian airmass builds into the region, temperatures will cool down with values returning closer to normal levels.

High temperatures on Friday ahead of the cold front will climb into the upper 70s to mid 80s. On Saturday, highs are expected to be in the upper 60s to mid 70s. Finally, on Sunday, highs will struggle to make it out of the 60s across much of the region. Overnight lows Friday night through Sunday night will be 40s for the most part (some lower 50s along parts of the RGV).

AVIATION

(00Z TAFS) Issued at 456 PM CST Sun Jan 4 2026

Generally light to gentle (5-10 knots) easterly winds continue at this time with mainly clear skies at KHRL and KMFE while some broken VFR (ceilings around 3,000 feet) clouds are reported above KBRO, streaming off the Gulf. Overnight, winds turn southeasterly and light to calm. Mainly clear skies and elevated humidity through the early nighttime hours is expected to set the stage for low stratus and/or patchy fog to develop, leading to LIFR/IFR/MVFR conditions til perhaps 13/14 Z Monday. Conditions should improve to VFR in the morning as southeasterly winds become breezy by the afternoon hours, around 10-15 knots, gusting to 20-25 knots.

MARINE

Issued at 1242 PM CST Sun Jan 4 2026

Favorable marine conditions with light to moderate winds and low to moderate seas (wave heights between 2-4 ft) will continue through Tuesday night. Wednesday afternoon/evening marine conditions could be come a bit more adverse to due breezy southerly winds ahead of a cold front. Moderate to Small Craft Exercise Caution (SCEC) conditions are possible. Adverse to potentially hazardous marine conditions (moderate seas to SCEC conditions) are expected to continue ahead and behind the cold front are then expected to continue through the remainder of the forecast period.

PRELIMINARY POINT TEMPS/POPS

BROWNSVILLE 63 83 67 84 / 0 0 0 0 HARLINGEN 60 84 64 86 / 0 0 0 0 MCALLEN 63 86 66 88 / 0 0 0 0 RIO GRANDE CITY 60 87 62 86 / 0 0 0 0 SOUTH PADRE ISLAND 67 76 69 77 / 0 0 0 0 BAYVIEW/PORT ISABEL 62 81 66 83 / 0 0 0 0

BRO WATCHES/WARNINGS/ADVISORIES

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