textproduct: San Juan

KEY MESSAGES

Issued at 250 PM AST Fri Dec 12 2025

* Choppy to rough seas and life-threatening rip currents are expected to continue through the weekend.across the islands, particularly from Friday through Sunday.

* Breezy to locally windy conditions are expected across the islands this weekend.

* Patches of moisture from the east will reach the islands later tonight into tomorrow and then tomorrow evening into early Sunday, increasing passing shower activity. Limited afternoon convection possible over northwest PR.

* For the U.S. Virgin Islands, passing showers will increase in frequency later tonight through Saturday.

* A nearby frontal system over the western Atlantic and an associated upper level trough will promote more unstable conditions to start the next workweek.

Short Term(This evening through Sunday)

Issued at 241 PM AST Fri Dec 12 2025

During the early morning hours, a surface disturbance moved across the region, producing isolated showers over the windward sectors of Puerto Rico. Rainfall totals generally reached around half an inch, with isolated areas receiving up to 1 inch across northern and eastern Puerto Rico. Radar estimates indicated only minimal accumulations across the U.S. Virgin Islands. Afterwards, mainly fair weather prevailed, as shown by radar and satellite imagery, with a drier airmass settling over the region. The 12Z sounding measured 1.5 inches of precipitable water, but more recent satellite data indicates values closer to 1.00 inch. Daytime highs reached the mid to upper 80s, with some coastal stations reporting low 90s. Across the higher elevations of Puerto Rico, temperatures remained in the 70s to low 80s. Winds became breezy, with several coastal stations recording gusts between 25 and 30 mph out of the east to southeast.

The short-term forecast remains on track, with variable weather conditions and breezy winds expected to persist through the weekend. Surface high pressure will strengthen and linger over the central Atlantic, supporting increasing east to southeasterly winds and breezy to locally windy conditions across the islands, at least through next Sunday. Model guidance continues to indicate increasing moisture due to disturbances moving through the trade winds, one tonight and another from Saturday evening into early Sunday.

During the daytime hours each day, lower precipitable waters (PWAT) values will dominate, fluctuating between below-normal and above- normal levels. As a result, mainly fair weather is expected, with only limited shower activity across western Puerto Rico (low chance), while the U.S. Virgin Islands and the windward sectors of Puerto Rico will see moderate to high chances of nighttime and early- morning showers. The highest moisture content, ranging from 1.8 to 2.0 inches (above normal), is expected Saturday afternoon and night. During this period, there will be a limited flooding risk across eastern Puerto Rico and the U.S. Virgin Islands, with the potential for ponding on roads, poor drainage issues, and a low chance of urban and small-stream flooding. During the rest of the period, there are no flooding concerns anticipated. A southeasterly wind pattern will continue to bring warmer air, leading to above- normal temperatures in the short term. However, the overall heat threat is expected to remain low for the remainder of the period.

Long Term(Monday through Friday)

Issued at 518 AM AST Fri Dec 12 2025

Global models have a wetter solution than previous days with the approaching frontal system over the western Atlantic and associated upper level trough promoting more unstable conditions through first part of the workweek. The 500 mb temperatures are expected to drop to around -6.5C and the precipitable water content is expected to remain near 1.75 inches, above normal levels for most of the period. The mid-to upper-level ridge is now expected to erode earlier and have little influence in the local weather conditions. Pooling of normal to above normal moisture content over the area will lead to weak surface troughs to move from the east on most days, increasing the chance of showers between 50-70% each day across the islands, with a slight chance of thunderstorm development over western PR in the afternoon hours. However, decided to not include them in the forecast as of now due to possible model variations.

At the surface, a broad high pressure will linger near and south of the Azores through the long term period. Meanwhile, a cold front over the western Atlantic should remain north of the region early in the forecast. This will promote a southeasterly wind flow, leading to warmer than normal temperatures before the onset of afternoon showers. Another surface high pressure is expected to build behind the front and over the western Atlantic during the second part of the week, bringing east to northeast trades and a cooler air mass.

AVIATION

(18Z TAFS) Issued at 250 PM AST Fri Dec 12 2025

VFR conditions for the terminals. E-SE winds at 13-20 kts, with gusts up to 28 kts through 12/23Z, decreasing after. An increase in VCSH/-SHRA is forecast during the overnight hours, these can promote brief MVFR conditions over eastern terminals. As VCSH/-SHRA move over the region, winds will increase again after around 13/13-14Z to 13-20 kt from the E-SE, with higher gusts and sea breeze variations.

MARINE

Issued at 250 PM AST Fri Dec 12 2025

A surface high pressure system will continue to build near the Azores through the weekend. A weak cold front and another surface high pressure system will move from the western Atlantic into the central Atlantic over the next few days. This pattern will promote moderate to locally fresh east to southeast trade winds across the local waters. Increasing winds and a long-period northerly swell will result in choppy to rough seas, mainly across the Atlantic waters and portions of the Anegada and Mona Passages. Small Craft Advisories remain in effect at least through tomorrow morning across the passages and through Sunday afternoon across the offshore Atlantic waters.

BEACH FORECAST

Issued at 250 PM AST Fri Dec 12 2025

A long-period northerly swell and increasing wind waves will create life-threatening rip currents along the north and east facing beaches of the islands over the next few days. A Rip Current Statement remains in effect for the northwest to northeast beaches of Puerto Rico, including Culebra, as well as St. Thomas and St. John. Beachgoers are urged to avoid swimming in these conditions, particularly through the rest of today and Saturday. The west and south-facing beaches of the islands will experience a moderate risk of rip currents. For specific location information, please visit weather.gov/beach/sju.

SJU WATCHES/WARNINGS/ADVISORIES

PR...High Rip Current Risk through Saturday afternoon for PRZ001-002- 005-008.

High Rip Current Risk through late tonight for PRZ012.

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

AM...Small Craft Advisory until 5 PM AST Sunday for AMZ711.

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

Small Craft Advisory until noon AST Saturday for AMZ723.

Small Craft Advisory until midnight AST tonight for AMZ741.