Marine Weather and Tide Forecast for Port Aransas, TX

DISCUSSION
Issued at 128 AM CDT Mon May 18 2026

We'll start off with analyzing the current environment. Our latest 00Z sounding shows PWAT values right at 2.0" (99th percentile) while satellite earlier, depicted splotches of PWATs up to 2.2". Needless to say, we are near climatological max already when it comes to atmospheric moisture. Streaks of showers and a few embedded thunderstorms have flown by to the northeast from the southwest, oriented with the 500mb shortwave trough. We'll continue to see these streaks of showers and occasional thunderstorms through Tuesday before coverage and chances ramp up significantly.

Rain chances ramp up to a medium (40-60%) chance Tuesday night as an inverted surface trough develops ahead of an approaching but dying cold front. However, convection earlier on in the day northward will likely develop outflow boundaries that can enhance storm's longevity as they move southward. Therefore, South Texas is in a marginal (level 1 of 5) risk of strong to severe storms Tuesday night into Wednesday morning. Given the significant elevated instability, DCAPE, and moisture in place, primary threats are large hail and damaging winds at this time.

A series of repeating mid-level shortwaves will pass over South Texas through this weekend as a more potent trough or cutoff mid- level low develops over northern Mexico and moves eastward into Texas. Near climatological max moisture in combination of these disturbances, will warrant a medium to high chance of showers and thunderstorms daily. Total rainfall through Saturday looks to range from around 1.50" along the coast to around 3.00" over northern counties from La Salle to Victoria counties. This is a good blend between the various long range ensembles. The GEFS lower along the coast of 1.00" but around 3.00" over the northern Nueces River Basin, the ECENS from 1.50 along the Rio Grande to near 3.5" over the Victoria Crossroads, and the GEM with a widespread 2.50-3.00".
Due to these rain amounts, and locally higher up to 5", much of South Texas will be under a marginal to slight risk of flash flooding Tuesday night through Friday. We'll also need to monitor river levels as action to minor flood stage will likely occur across the state as upstream flow makes its way down in combination of additional heavy rains. Multiple rounds of rain will increase soil moisture and lead to more efficient runoff the longer we get into the event.

Dewpoints climbing into the mid to upper 70s and temperatures climbing into the upper 80s to near 100, will bring a moderate to major risk of heat-related impacts across South Texas today and Tuesday. Max heat indices will range from 100-110 with greatest impacts over the Brush Country where there will be fewer clouds in the afternoons.

Persistent strong onshore flow with swell periods of 7-8 seconds warrants a high risk of rip currents, causing dangerous swimming conditions. These conditions will also lead to another threat for minor coastal flooding early this morning during high tide. We'll need to keep a close eye on webcams with how much wave runup we get, but confidence is low with the lack of buoy observations.

Fun fact at Corpus Christi: Total precipitation of at least 2.0" from May 19th through May 23rd has occurred 11 out of the 139 years in the period of record, 7.9% of the time!

AVIATION
(12Z TAFS)
Issued at 559 AM CDT Mon May 18 2026

The MVFR cloud deck will continue through 14Z then begin to lift to VFR CIGs and continue through the afternoon. Due to the isolated nature of shower activity today, VCSH were added to all terminals, though more impacts to flight categories come this evening with any thunderstorm that develops off the higher terrain in northern Mexico. As such, a TEMPO group was added for KLRD. If this activity holds on as it moves through the Brush Country, it might bring a few periods of lower CIGs /VIS for KALI, though confidence is low for this.

MARINE
Issued at 128 AM CDT Mon May 18 2026

Moderate to fresh (BF 4-5) southeasterly breeze will persist through Tuesday night. The Small Craft Advisory is now in effect through Tuesday morning for all waters due to sustained winds around 20 knots and frequent gusts to around 25 knots. Seas will also generally range from 5-7 feet. Southeasterly flow weakens to gentle to moderate (BF 3-4) Wednesday into this weekend. Low to medium rain chances begin Tuesday night through Wednesday night, then increase to a medium to high chance, 50-70%, Thursday into this weekend.

FIRE WEATHER
Issued at 128 AM CDT Mon May 18 2026

No elevated fire weather conditions are expected through this week.
Moisture will continue to increase, causing minimum relative humidity values to stay above 40%. Low rain chances through Tuesday, increase to a medium to high (40-80%) Tuesday night into this weekend

PRELIMINARY POINT TEMPS/POPS
Corpus Christi 91 80 90 78 / 20 20 20 50 Victoria 91 78 91 75 / 20 20 20 50 Laredo 100 79 99 76 / 20 20 20 50 Alice 95 79 94 77 / 20 20 20 50 Rockport 90 80 89 79 / 20 20 20 50 Cotulla 99 79 98 74 / 20 20 20 50 Kingsville 93 80 91 77 / 20 20 20 50 Navy Corpus 88 81 87 80 / 20 20 20 50

CRP WATCHES/WARNINGS/ADVISORIES
TX...Coastal Flood Advisory until noon CDT today for TXZ345-442-443- 447.

High Rip Current Risk through Tuesday evening for TXZ345-442-443- 447.

GM...Small Craft Advisory until 9 AM CDT Tuesday for GMZ231-232-236- 237-250-255-270-275.