textproduct: San Juan

KEY MESSAGES

Issued at 226 PM AST Sun Jan 18 2026

* Marine and coastal conditions remain hazardous, though they are gradually subsiding. Seas are still rough with an ongoing risk of rip currents. Small Craft operators and beachgoers should continue to exercise caution and follow any posted warnings and advisories.

* Trade wind-driven showers will persist, moving from time to time and producing slippery road conditions and ponding of water in low- lying and poor drainage areas.

* Breezy to windy conditions will continue, and although winds are slowly easing, unsecured items may still be blown around, especially in more exposed locations.

Short Term(This evening through Tuesday)

Issued at 226 PM AST Sun Jan 18 2026

Mostly fair conditions prevailed during the morning hours. Passing showers moved mainly across the waters, a few moving over portions of St. Croix in the U.S. Virgin Islands and eastern portions of Puerto Rico. Breezy to windy conditions continue across the islands, as CWOP/ASOS stations reported maximum wind gusts between 30 and 33 mph over coastal areas (31 mph at the Henry E. Rohlsen International Airport in St. Croix, VI, and 33 mph at Camp Santiago in Salinas, PR) and higher elevations. Todays 12z RAOB showed slightly lower PWAT values compared to the 00z (from 1.36 to 1.18 inches), due to a drier airmass that filtered into the region early today. Considering that HIRES models do not suggest significant rainfall accumulation for this afternoon, shallow convection is the most likely scenario, with passing showers moving through the western portions of Puerto Rico.

No major changes were introduced to the short-term forecast, as variable and breezy to windy (winds between 15 - 25 mph) conditions are expected to continue across the CWA. The wind pattern will continue from the east to east-southeast due to a broad surface high pressure over the Central Atlantic. Based on the latest model guidance, the moisture content is expected to increase late tonight due to a patch of moisture. According to the deterministic guidance of the GFS and ECMWF, PWAT values are expected to increase (between 1.2 and 1.4 inches), typical for the season. An increase in frequency of showers can be expected, particularly affecting portions of the U.S. Virgin Islands and windward sections of Puerto Rico. Due to strengthening winds, short-lived showers should not leave significant rainfall accumulations. The presence of a mid- level ridge will dominate most of the weather pattern across the local area, as warmer-than-normal 500 mb temperatures (around -4 degrees Celsius), low 700 - 500 mb lapse rates (between 5 and 5 degrees Celsius per kilometer), and lower RH content in the 700 - 500 mb levels indicate unfavorable conditions for deep convection. Hence, from Monday onwards, the variable conditions will continue due to abundant low level moisture content across the CWA, with passing showers across windward sections during the morning hours and shallow afternoon convection over western Puerto Rico, along with the U.S. Virgin Islands streamers. The highest accumulations may be expected over western PR, with mainly localized ponding of water over roadways, urban, and poorly drained areas.

Long Term(Wednesday through next Saturday)

Issued at 413 AM AST Sun Jan 18 2026

As noted in previous discussions, model guidance continues to indicate a humid and unsettled pattern throughout the long-term period across Puerto Rico and the U.S. Virgin Islands. The most unstable conditions are expected on Thursday, with unsettled weather persisting through Saturday. Precipitable water values rising above 1.75 inches after Wednesday reflect above-normal moisture associated with a deep tropical plume, enhancing overall shower coverage.

This pattern will support thunderstorms and periods of moderate to locally heavy rainfall, increasing the potential for localized flooding, particularly in urban, poor drainage, and low-lying areas. Repeated showers over the same locations could worsen runoff issues, while frequent lightning may pose hazards to outdoor activities. Although east to northeast winds of 17 to 20 mph should help limit widespread flooding, locally enhanced rainfall will remain possible, especially in terrain-favored areas.

Temperatures are expected to trend back toward seasonal norms by Thursday, but persistent high moisture and cloud cover will maintain humid conditions through the remainder of the period.

AVIATION

(18Z TAFS) Issued at 226 PM AST Sun Jan 18 2026

Mainly VFR conds are expcd across all terminals, with VCSH due passing SHRA throughout the TAF prd. VCSH will continue aft 18/23z, reducing CIGs/VIS at exposed terminals (ISX, IST, and JSJ). Winds from the E-ESE will slgtly weaken tonight, around 18/23z, btwn 8 - 10 kt at PR TAF sites, while IST and ISX can expc around 12 kt. Strengthening wind will return by 19/13z, btwn 15 - 17 kt and gusts up to 24 - 25 kt.

MARINE

Issued at 226 PM AST Sun Jan 18 2026

Broad surface high pressure over the central Atlantic will continue to influence the regional waters through at least tonight. Fresh to locally strong east winds will persist, maintaining choppy to rough seas, although conditions are expected to gradually subside later today. Small Craft Advisories remain in effect at least through this afternoon, as hazardous marine conditions will continue, especially across the offshore Atlantic waters and passages. Mariners should continue to exercise caution until seas and winds further diminish.

BEACH FORECAST

Issued at 226 PM AST Sun Jan 18 2026

A High Rip Current Statement remains in effect for the north and east-facing beaches of Puerto Rico, including Culebra, and the U.S. Virgin Islands through 6 AM AST on Monday. While marine and surf conditions are slowly subsiding, hazardous rip current conditions persist, and the risk remains high along exposed beaches. Residents and visitors are urged to continue following the warning flag system and to favor beaches with lower rip current risk, such as those along the western and southern coasts of Puerto Rico.

In addition, breezy to locally windy conditions continue along coastal areas, which may still result in unsecured objects being blown around, particularly in the most exposed locations. Beachgoers should remain cautious both in and near the water until conditions improve further.

For localized and updated risk levels, visit weather.gov/beach/sju.

SJU WATCHES/WARNINGS/ADVISORIES

PR...High Rip Current Risk through late tonight for PRZ001-002-005- 008-012.

VI...High Rip Current Risk through late tonight for VIZ001-002.

AM...Small Craft Advisory until midnight AST Monday night for AMZ711- 723.

Small Craft Advisory until 6 PM AST this evening for AMZ712-716- 726-733-741.