textproduct: Brownsville/Rio Grande Valley

KEY MESSAGES

Updated at 538 AM CST Tue Dec 23 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

(12Z TAFS) Issued at 538 AM CST Tue Dec 23 2025

Patchy fog and low stratus with low winds prevail across Deep South Texas early this morning. A mix of VFR to LIFR conditions continue across the area. Full VFR conditions are expected to develop mid to late morning as southeast winds increase. Patchy to areas of fog and low stratus return later this evening and overnight. MVFR to LIFR conditions will possible late tonight, especially at MFE.

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 83 67 83 66 / 20 10 10 0 HARLINGEN 84 64 83 63 / 30 0 10 0 MCALLEN 87 68 86 67 / 30 10 10 0 RIO GRANDE CITY 86 64 86 65 / 20 10 0 0 SOUTH PADRE ISLAND 76 69 76 69 / 20 10 10 0 BAYVIEW/PORT ISABEL 81 65 81 65 / 20 10 10 0

BRO WATCHES/WARNINGS/ADVISORIES

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