textproduct: Brownsville/Rio Grande Valley

KEY MESSAGES

Updated at 1022 PM CST Mon Dec 22 2025 * Patchy fog and dense fog are expected tonight, especially across the ranchlands. Additional dense fog is likely Wednesday morning and Christmas Eve into Christmas morning.

* There is a brief low to medium (20-30%) chance of showers and isolated thunderstorms Tuesday afternoon.

* A strong cold front with cooler temperatures works towards the border late Sunday into Monday.

DISCUSSION

Issued at 1022 PM CST Mon Dec 22 2025

The subtropical ridge generally holds through most of the forecast period, maintaining well-above normal temperatures, over 10 degrees above normal, through Christmas and into the last weekend of 2025. Weak lift and instability aloft paired with surges of moisture help kick up a low to medium (20-30 percent) chance of showers and isolated thunderstorms Tuesday afternoon and a low (less than 15 percent) chance of mainly offshore showers Wednesday. A strong cold front near the end of the forecast period arrives late Sunday into Monday, bringing back a medium (30-40 percent) chance of rain and cooler temperatures, to at least near normal, if not a few degrees cooler.

Confidence in dense fog tonight has not been as good as the past few nights, with the best chance of development across the ranchlands. NBM, SREF, and HREF probabilities all keep a low to medium (15-30 percent) chance of visibility reduced below 1 mile late tonight, mainly after 4 or 5 AM. Will issue an SPS for now for occasional dense fog and let the overnight crew monitor for any upgrades. There is a better signal for fog into Wednesday morning and again Christmas Eve into Christmas morning. Will continue to monitor and brief the North Pole on the potential need for Rudolph across Deep South Texas.

AVIATION

(06Z TAFS) Issued at 1022 PM CST Mon Dec 22 2025

VFR conditions are expected to give way to MVFR and potentially IFR conditions late tonight with patchy fog and dense fog developing late and a lower stratus deck arriving from the south. VFR ceilings return by mid morning Wednesday.

MARINE

Issued at 1022 PM CST Mon Dec 22 2025

Southeasterly onshore flow continues into this weekend with a gradually increasing swell. The chance of rain diminishes but continues into Wednesday. Patch fog and dense fog will reduce visibility at times along the bay and nearshore waters.

PRELIMINARY POINT TEMPS/POPS

BROWNSVILLE 68 83 67 83 / 10 20 10 10 HARLINGEN 65 84 64 83 / 10 30 0 10 MCALLEN 69 86 67 86 / 10 30 10 10 RIO GRANDE CITY 66 86 65 86 / 0 20 10 0 SOUTH PADRE ISLAND 69 76 70 76 / 10 20 10 10 BAYVIEW/PORT ISABEL 67 80 65 80 / 10 20 10 10

BRO WATCHES/WARNINGS/ADVISORIES

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