textproduct: San Juan

KEY MESSAGES

Issued at 214 AM AST Mon Dec 15 2025

* A surge in moisture associated with a pre-frontal trough moving to the north of the area will promote more unstable and wet conditions during the first half of the workweek across the U.S. Virgin Islands and Puerto Rico.

* Choppy to rough seas are expected to continue across the offshore Atlantic waters through at least today.

* A northwesterly swell is forecast to arrive by midweek, deteriorating marine and coastal conditions through the upcoming weekend.

Short Term(Today through Wednesday)

Issued at 214 AM AST Mon Dec 15 2025

A surge in moisture associated with a pre-frontal trough moving to the north is expected in the short-term period. The precipitable water content (PWAT) is expected to increase to near 1.75 inches late today, with no significant change in moisture levels through the rest of the short-term period. Latest satellite imagery indicates an area of cloudiness and showers moving over the Leeward Islands into the Anegada Passage. This area will then reach the USVI early this morning and spread across PR throughout the day. As the local area lies between the front and a distant surface high pressure, winds will generally persist from the east to southeast at 5 to 15 knots. For Tuesday and Wednesday, no significant variations in moisture content are expected. However, the 500mb temperatures are forecast to be the coldest on Tuesday afternoon, around -6.5C, which should favor heavier showers and isolated thunderstorm development. Ponding of water in roads and other poor drainage areas can be expected each day across the islands, with a higher chance of urban and small stream flooding on Tuesday in PR.

Long Term(Thursday through Monday)

Issued at 214 AM AST Mon Dec 15 2025

The forecast remains on track with previous discussions. A building surface high-pressure system over the western Atlantic will continue to push lingering moisture from a frontal boundary into the local area from Thursday into Friday. This will increase the frequency of passing showers across Puerto Rico and the U.S. Virgin Islands, particularly during the morning hours across the windward portions. As the surface high continues to move over the Atlantic Ocean, another frontal boundary will move east of the eastern coast of the CONUS, promoting a northeasterly wind flow across the area. Under this pattern, cooler temperatures will be felt across the region during the upcoming weekend. By Sunday, another surface high pressure behind the front is expected to strengthen north of the local area, bringing slightly drier conditions; nonetheless, patches of moisture will continue to move into the islands, promoting showers from time to time.

AVIATION

(06Z TAFS) Issued at 214 AM AST Mon Dec 15 2025

Mainly VFR conditions are expected early in the fcst period. However, SHRA en route from the Leeward Islands will reach the USVI terminals btw 15/12-16z, this may lead to tempo MVFR conds, particularly at TIST. Additional SHRA is expected to develop in and around TJSJ and TJBQ btw 15/16-22z, which could lead to brief MVFR cigs. Winds will increase 8-12 kt from the ESE, with sea breeze variations at TJSJ/TJBQ aft 15/14z.

MARINE

Issued at 214 AM AST Mon Dec 15 2025

A surface high-pressure system across the eastern into central Atlantic will continue to promote moderate to locally fresh east to southeast winds across the local waters today. Wind-driven seas are promoting hazardous marine conditions for small craft operators across the offshore Atlantic waters, where a Small Craft Advisory remain in effect at least through Monday morning. A cold front and another surface high-pressure system will move from the western Atlantic into the central Atlantic over the next few days, weakening the pressure gradient and allowing for gentle to moderate winds from late today and Tuesday. By midweek, increasing winds and a northwesterly swell will likely deteriorate marine conditions once again.

BEACH FORECAST

Issued at 214 AM AST Mon Dec 15 2025

A moderate risk of rip currents will continue along most beaches of the islands through mid-week. This means that life-threatening rip currents are possible in the surf zone, and beachgoers are encouraged to exercise caution. The moderate risk of rip currents is expected to prevail across north-facing beaches of Puerto Rico, Culebra, and the U.S. Virgin Islands, with a low risk elsewhere. Remember that even when the risk is low, life- threatening rip currents can still occur, especially near groins, jetties, reefs, and piers.

By midweek, beach conditions are anticipated to deteriorate again due to increasing winds and a northwesterly swell spreading across the local Atlantic waters. Stay tuned to the forecast! For specific location information, please visit weather.gov/beach/sju.

SJU WATCHES/WARNINGS/ADVISORIES

PR...None. VI...None. AM...Small Craft Advisory until noon AST today for AMZ711.